* * * * * * * * * * * * * * * * * * *
The Pattern of India-Burma Operations, 1943
THE elaborate plans formulated in 1942 for the reconquest of Burma in the spring of 1943 had, for the most part, been laid away by January with a promise from the CCS at Casablanca that the offensive might be undertaken the following November. The amphibious operation in the south had been canceled by the British, the Y (Yunnan) Force had then been withheld from participation in the offensive on orders from the Generalissimo, and Stilwell was compelled by circumstances to postpone commitment of the X (Ramgarh) Force. Other British operations planned for central and southern Burma were then emasculated, and though some activity was attempted, it proved ineffectual. Brig. Orde Wingate did lead the 77 Brigade into Burma in February and got 200 miles behind the Japanese lines. But Wingate was without strategic objectives, and after his forces suffered heavy losses, he withdrew in June. The plan to have the 4 Corps at Imphal in Assam advance to the Chindwin River and establish positions between Kalewa and Sittaung was whittled down by January 1943 to mere offensive patrols. Farther south the advance down the Mayu Peninsula toward Akyab had gotten under way on 16 December. By March 1943 the British were in Rathedaung, twenty-five miles north of Akyab, but at that point the enemy infiltrated behind their positions and the British forces began retirement to the lines held by them in December.
There was, however, one phase of Stilwell's plan for 1943 that was begun and continued with success--the construction of the Ledo Road. From the time Stilwell escaped from Burma in May 1942 he had proclaimed the necessity of a military pincer movement from upper Assam and Yunnan for the reconquest of northern Burma to gain control of a
road trace from India to China. Early in 1941 the British had begun a road leading from Ledo to Myitkyina and had constructed the first five miles of the course eastward from Ledo. Stilwell's plan called for resumption of this work by Americans, and work began on 25 December 1942. By midsummer of 1943 the road had been pushed across the frontier into Burma and was approaching Shingbwiyang.
Aside from the work done on the Ledo Road, the weak offensive movements of the British toward Akyab and in the region of the Chindwin, and the expedition under Wingate, military operations in Burma until the fall of 1943 were limited to the activities of the RAF and the AAF. On 1 January 1943, RAF operations in India and Burma were conducted by four groups. The 222 Group and 225 Group, located respectively at Colombo and Bangalore, were under Air Headquarters, India Command. The 221 Group at Calcutta and 224 Group at Chittagong were under Air Headquarters, Bengal, Air Vice Marshal T. M. Williams in command. The 222 and 225 Groups were responsible for general reconnaissance and for the defense of their areas. Coordination of RAF and AAF activities against the Japanese was through headquarters of the India Air Task Force, located at Barrackpore, and the RAF Bengal Command. Relations were most cordial, and "operations conferences" between the two forces were held each day to plan for activities throughout the following twenty-four hours.
Although the Americans and the British had been gathering strength throughout the second half of 1942, neither the Bengal Command nor the IATF was sufficiently strong in January 1943 to challenge seriously the Japanese air superiority over Burma.* Nevertheless, the Allies had the courage to assume the offensive against the enemy, and before the end of the year they had grown both in experience and in newly accumulated strength to gain supremacy early in 1944.
The British, of course, were engaged against the enemy in giving ground support to troops in the Akyab offensive and in the activities east of Imphal. The RAF also did its share in defense of Allied airfields and in offensive attacks on the Japanese bases. The pattern of operations followed by the Tenth Air Force was almost identical with that of the RAF except that the Americans were not involved in the land battles which were fought during the first three or four months
* In January 1943 the British had a total of some fifty squadrons in the whole India Command, of which about thirty-five were operational and deployed. Deployment outside the Bengal Command was concentrated chiefly around Ceylon and in northwest India.
of 1943 and thus were able to concentrate their attention upon three objectives. First, they sought to defend their airfields in Assam while challenging the Japanese air force in northern Burma in protection of the Hump route. Second, by heavy bomber operations in the south, the Americans attempted to cut off Burma from Japanese supplies and reinforcements coming in ships through the Andaman Sea or crossing overland by rail or road from Thailand. Third, an effort was made by medium bomber operations in central Burma to disrupt Japanese communications between Rangoon and the battle front in the far north.
Defense of the Assam Airfields
Immediately following the Japanese bombing and strafing attacks on installations in Assam during October 1942, all available American fighters had been rushed to that vital area. Only two fighter squadrons were then in India, the 25th and 26th Squadrons of the 51st Group, and upon this small force was to rest the responsibility for aerial defense until late the following summer.1 Protective weather of the monsoon season promised some relief in May, but prior to that time the group commander, Col. John F. Egan (vice Col. Homer L. Sanders, 23 March 1943), faced a nearly impossible task. With only forty planes, inferior in many respects to the Japanese fighters then in the vicinity, he was expected to fend off further bombing attacks and at the same time provide protection for Hump-flying transports. Formation flying by the transports was impossible because of inadequate airdrome facilities, so that fighter planes had to be airborne over the paths of the single transports to give them even a modicum of safety from enemy raiders. Similarly, because of the shortcomings of the air warning net, planes had to be aloft constantly over Assam to prevent repetition of attacks such as those of October. Patrols, then, were necessarily small, far too small to be effective against a determined enemy air offensive.
Meanwhile, an enemy movement north from Myitkyina, begun in January in connection with a similar drive toward Yunnan, had advanced sufficiently to threaten Fort Hertz in northern Burma. Fort Hertz represented the last vestige of British authority in Burma, and its loss could easily alienate those Burmese who had remained loyal. Among these, the Kachins were especially valued as allies, having demonstrated their ability as guides, scouts, intelligence agents, and jungle fighters. To Americans, Fort Hertz was no mere symbol. It was a forward emergency base for patrols protecting Hump flyers, an
important weather and radio station through which information from air warning posts cleared, and a center of native intelligence activities which were providing vital military information. Moreover, its loss might result in establishment of an enemy fighter base from which the whole Hump operation could be interrupted. More important yet, perhaps, was the fact that once enemy troops were in Fort Hertz they could flank the entire route of the Ledo Road.2
Since protection of Fort Hertz might be interpreted as coming within the compass of defense of ICWATC, the Assam fighters took on another duty. Providing a defense now would be less expensive than mounting an offensive later, and all agreed that Fort Hertz must be held. Some 750 Kachins and a company of Ghurkas were astride the enemy line of advance, but they needed reinforcements, and the only troops then available were American-trained Chinese at Ramgarh. Protection of the Ledo project was deemed more important in the immediate future, however, and the Chinese troops were deployed to check a possible advance up Hukawng valley. Consequently, it was months before any reinforcements reached Fort Hertz. Meanwhile, it fell to the 25th and 26th Squadrons to help the British forces in their delaying tactics.3 The Japanese, moving forward toward their goal, dug in as they went, establishing supply dumps, repairing roads, building bridges, and in general strengthening their position north and west of Myitkyina. In answer to desperate calls for air assistance, the small Assam force increased its offensive missions as much as resources would permit. In the areas north of Myitkyina enemy camouflage discipline was excellent, making it almost axiomatic that any target spotted from the air was too insignificant to be attacked. With the aid of exact information from the ground defenders, however, the Americans successfully bombed and strafed many well-hidden targets. Eventually the 51st Group evolved a five-point program to help stem the enemy advance, meanwhile preventing the Japanese ground forces from benefiting from direct aerial support. The program included: (1) persistent strafing and "fragging" of trails north of Sumprabum, in close support of British colonial troops; (2) making Sumprabum untenable by demolition and incendiary bombs; (3) persistent fighter sweeps against motor convoys, troop concentrations, and supply dumps along the road from Myitkyina to Sumprabum; (4) dive-bombing assaults against bridges at those points which would create most formidable difficulties to the enemy line of communication; (5) bombing attacks in
strength against main bases and nerve centers at Myitkyina and Mogaung.4
In this program the fighters received some help from bombers. The B-24's of the Fourteenth Air Force sometimes bombed the key points in the area on their freight-hauling trips to and from Assam, and B-25's occasionally struck targets in upper Burma. The burden, however, fell to the fighters. The results of their missions could seldom be assessed, but pilot morale was kept high by frequent reports from ground forces on successful missions.5
In the face of the best Allied efforts, however, Japanese ground forces edged northward. At the same time the enemy's most vital supply line, the railway into Myitkyina, continued to function. Only by destroying several bridges could the Americans hope to stop traffic over the rail line for any appreciable length of time, and P-40's were not then equipped to carry bombs large enough to accomplish this objective. Plans were made to interrupt the campaign against communications in central Burma long enough for B-25's to bomb out these bridges; but Yankee ingenuity stepped into the breach, and it was never necessary to bring in the bombers. Lt. Col. John E. Barr, executive officer of the 51st Group, proved by a series of daring experiments that the P-40's could be modified to carry the 1,000-pound bombs that had been imported for the B-25's to use.6 Once the new technique was mastered, the P-40's regularly carried this size of bomb, twice their previous bomb load. The new "B-40's" soon became accurate and destructive dive bombers, and the attacks against bridges were far more successful. While they still were not able to block the railway entirely, they did break it with enough frequency to make strafing of stranded rolling stock particularly rewarding. Bombings of railway bridges at critical points were effective enough to induce fast-working Japanese construction crews to take the precaution of building by-pass bridges.7 Before the monsoon came, the American fighters had forced the enemy to restrict troop and supply movements to the hours of darkness. The dive bombers also found their new bomb to be quite effective against enemy airdromes and kept the crews at Mogaung and Myitkyina busy repairing damage. In May torrential rains multiplied the inconveniences provided by the American fighters so that the Japanese were forced to halt their drive just north of Sumprabum.8
As anticipated, the monsoon ruled out all flying in Assam and northern Burma for weeks at a time, but as the summer of 1943 dragged on,
the 51st ran missions as often as weather permitted. Work was pushed on additional fighter fields, and training of replacement pilots made some progress. In July a brief clearing of the weather allowed a short flurry of missions, but in August the monsoon closed in again. Infrequent reconnaissance flights, however, revealed that the enemy was still stalled above Sumprabum.9
In September arrival of the 80th Fighter Group from Karachi and the transfer of the two remaining squadrons of the 51st Group to the Fourteenth in China broke the monotony of the rainy season in Assam. Originally trained on P-47's and scheduled for movement to Europe, the 80th had been forced to go through operational training at Karachi to become accustomed to the P-40's which they were to fly in combat.10 When they finally arrived in Assam there was a wholesale shuffling of personnel between this new group and the 51st so that the Assam defense would not be left entirely in the hands of inexperienced pilots. The 80th Fighter Group, comprising the 88th, 89th, and 90th Squadrons under the command of Col. Ivan W. McElroy, was equipped with P-40N's, which were better climbers than the heavier models used by the 51st.11
In the few remaining weeks of the monsoon, men of the 80th became accustomed to their surroundings and adopted much of their predecessors' routine. They flew patrols, made reconnaissance flights and weather checks, escorted transports on food-droppings, and occasionally bombed and strafed enemy-occupied areas. They also adopted the 1,000-pound bomb as the standard weapon for use against major targets. Rarely did they see enemy aircraft; and antiaircraft fire encountered was generally light and ineffective.12
Meanwhile, General Haynes, after long service in the theater, had been returned to the Zone of the Interior, Brig. Gen. W. D. Old assuming command of American Air Base Command I (formerly AAABC) and Col. Torgils Wold taking over command of the IATF. Old, having served with the Assam-Burma-China Ferry and as chief of staff of the Tenth Air Force, was of course well informed on the situation in Assam, and Colonel Wold as commander of the 341st Bombardment Group had long since become familiar with operating conditions in Bengal and Assam.13
Before the monsoon had entirely disappeared the situation in Assam was further improved by the arrival of the 311th Fighter-Bomber Group under Col. Harry R. Melton, Jr. One of its squadrons had been
inactivated upon arrival in the theater and much of its personnel transferred to the 459th (P-38) Fighter Squadron, whose flight echelon had recently arrived from the Mediterranean theater. The 459th, assigned to the 80th Fighter Group, was sent to Kurmitola in Bengal, where it operated in conjunction with the B-25 squadrons. The other three squadrons of the 311th Group--the 528th, 529th, and 530th--were equipped with A-36's and P-51A's. Thus the fighter strength of the Tenth Air Force was greatly increased in the space of a few weeks. The number of squadrons jumped from two to seven, and instead of having old-model P-40's for every conceivable kind of mission, P-40N's, P-51A's, A-36's, and P-38's were available, and all had superior altitudes. For the first time there could be a division of labor among the fighters in the Tenth.14 Versatility of the fighter force promised to make it more effective in countering enemy moves in Burma. P-38's of the 459th in the south soon gave bombers their first long-range fighter escort, while in Assam the P-40's took over patrol duties, interpolating an occasional bombing and strafing mission. P-51A's and A-36's engaged largely in air support to ground forces moving down from Ledo in advance of the road-builders, but they frequently flew reconnaissance and patrol missions. Late in November 1943, the 530th Squadron was pulled down into Bengal to fly escort to bombers on a series of special missions against Rangoon.15
Before the new fighter and fighter-bomber squadrons had time to be lulled into a feeling of security by enemy inactivity, the Japanese again challenged American air ascendency over northern Burma. During the wet season they had repaired many old airfields and had built several new ones, and on 13 October their fighters appeared over Sumprabum in strength to harass the Hump flyers. Probably aided by ground radiomen, they easily evaded American patrols and attacked passing transports, During the day they shot down one CNAC transport, one ATC C-46, and one ATC C-87, while damaging one B-24 of the Fourteenth and two C-47's of a troop carrier squadron. American fighter patrols were increased from four to eight planes but with little effect. On the 16th, three A-36's of the 311th failed to return from a mission over Sumprabum. On the 20th, another C-46 was lost and three days later three others were missing. On the 27th, still another C-46 was shot down and two formations of freight-hauling B-24's of the Fourteenth Air Force were attacked. The B-24's, perhaps mistaken for C-87's, destroyed eight fighters and damaged several others.16
Meanwhile General Old, consulting with Tenth Air Force and ATC, put into effect a policy which was designed to save the transports from further attacks. In spite of the greater altitude at which they would have to fly, henceforth all transports were to cross well north of Sumprabum. A radio control station was set up at Fort Hertz to keep in constant contact with transports and fighter patrols, while immediate attention was given to destruction of all enemy airfields in central Burma from which the fighters might be operating. As an example of the treatment accorded these airdromes, the field at Myitkyina was attacked on 13, 18, 21, 27 October, on 3, 8, 9, 25, 30 November, and on 2, 4, 11, 18, and 28 December 1943, most of the attacks being carried out by P-40's bearing variously fuzed thousand-pounders. Strafers worked over the fields, giving special attention to antiaircraft positions.17 It is impossible to determine which of the precautions was most effective in stopping depredations on the Hump flyers, but in November no transports were shot down, and in December only two were lost to enemy action. In the latter month, however, enemy air activity resulted in the loss of a B-25 and four troop carrier C-47's in a single day.
The Japanese once more attacked Assam, on 13 December 1943. They had tried to confound the defenders by entering the warning net almost daily for several weeks without coming in to attack. Then on the appointed day, twenty twin-engine bombers escorted by twenty-five fighters appeared over Dinjan only twelve minutes after the alert was sounded. Bombs were away before interceptors made contact, but their aim was poor and little damage resulted. They were caught by American fighters before they could get out of the area and suffered heavy losses. And just after they had shaken off the original interceptors the enemy formation ran into other American fighters returning from a mission to Bhamo. Again the Japanese suffered losses. In all, twelve of twenty bombers were shot out of the air and five of the escort were lost. Bad bombing and the enemy's accidental meeting with returning American fighters turned the mission into a fiasco, but the Japanese had once more demonstrated that they could slip through the Assam warning net and drop their bombs before they could be intercepted.18
Enemy Communications in Burma
While the relatively few fighter planes over north Burma were carrying out the primary mission of the Tenth by protecting the China
ferry, the remainder of the force, medium and heavy bombers, was engaged in the secondary but nonetheless important task of attempting to destroy enemy installations, supply routes, and lines of communications into and across Burma.18 Thus, indirectly, they sought to aid the fighters by preventing a build-up of Japanese forces in the critical northern region. In view of the rather unusual circumstances under which the bombers had to operate, it may be well to consider in detail the transportation system of Burma.
Nearly as large as Texas, Burma has been likened to a giant wedge driven between India and China. On three sides the country is locked in by a massive ring of mountain ranges which form most of its 3,200 miles of land frontier, and prior to the completion of the Burma Road, it had no rail or road connection with China or India. Branching off from the Himalayas at the northern tip of Burma, the Patkai-Naga Hills, with peaks rising to approximately 20,000 feet and valleys of extremely dense jungle, interposed an effective bar to transportation between Assam and northern Burma. It was over this range that the Assam fighters had to fly daily. Farther to the southwest an extension of that range, the Arakan Yomas, with peaks up to 10,000 feet, stretches to the shores of the Bay of Bengal, preventing land communications between India and lower Burma. On the China-Thailand side the Himalayan range branches out into numerous parallel north-south chains, extremely high along the China border, tapering gradually in the Shan States, and stretching far down into the Malay Peninsula. So on the east, too, Burma was long isolated from its neighbors by rugged and forbidding mountains.20 In shape and contour Burma itself resembles a slightly cupped hand, a tumbled mass of parallel ridges running north and south giving the palm a corduroy-like appearance. This central basin, its ridges dwindling in altitude toward the middle, extends from Fort Hertz in the north to the Bay of Bengal, varying in width from 100 to 150 miles. North-south ranges hinder lateral traffic, but the valleys between have developed into heavily traveled routes. Upon the southward-flowing rivers, most important of which is the Irrawaddy-Chindwin, and upon motor roads and rail lines closely paralleling their courses, normally passes the bulk of freight. After the Japanese victory of 1942, this system became the lifeline of enemy occupation forces.21
The Japanese did not take full advantage of the system of motor roads, having chosen to use most of their motor transport to move
supplies from terminals of the railway system to the outlying posts and stations. Under Japanese occupation, river traffic also was reduced. The British had destroyed numerous river craft during their retreat, and subsequently the RAF had attacked all types of craft plying the Irrawaddy-Chindwin.22 Naturally the rail system from Rangoon to Mandalay and Myitkyina became the chief LOC of enemy armies in northern Burma and along the Salween front.
Railway Transportation in Burma
The Burma rail net consisted of some 2,000 miles of meter-gauge, single-track lines, extending from Ye on the Malay Peninsula to Myitkyina on the upper Irrawaddy and completely isolated from rail systems of neighboring countries to the north and west. A line from Ye
led through Thanbyuzyat, western terminal of the Bangkok-Moulmein line which the Japanese had recently started, northward into Moulmein. Broken by ferries over the Salween estuary and the Sittang River farther north, this line joined the Rangoon-Mandalay trunk line at Pegu.23
From Rangoon a branch line moved northwestward to Prome on the Irrawaddy and thence southward to Bassein. The line of chief importance, however, was that stretching north from Rangoon past Pegu, where it was joined by the line from Ye and Moulmein, northward along the Sittang valley toward Mandalay. This backbone of the entire rail net of the country continued from Mandalay, following the upper Irrawaddy valley to the extreme northern terminal at Myitkyina.24
Lateral spurs branched off the Rangoon-Mandalay-Myitkyina trunk to serve various parts of the central basin. North of Pegu, at Pyinmana, a track ran northwestward almost to the Irrawaddy, stopping at Kyaukpadaung, not far from the oil fields at Chauk and Yenangyaung. Farther to the north on the main line was Thazi, most important junction between Pegu and Mandalay. Here one spur extended east to Shwenyaung, near the Shan capital of Taunggyi, giving a rail outlet to the Shan States region and connecting with trails from Thailand. Westward from Thazi a second spur through Meiktila reached Myingyan on the Irrawaddy and then rejoined the main line at Paleik, thus providing an alternate connection between Thazi and Paleik. On the short run from Paleik into Mandalay, however, all northbound traffic converged into a single line.25
At Myohaung yards in Mandalay all rolling stock was rerouted for ultimate destinations. One vitally important line moved out northeast to Lashio where supplies for the Japanese Salween armies were processed and transshipped to motor conveyances. A short track also ran from Mandalay northward to Madaya, a small mining town, but the heaviest traffic flowed west and north toward Yeu and Myitkyina. Just out of Mandalay this line crossed the Irrawaddy via ferry, by-passing the Ava bridge which the British had demolished, entered Sagaing and passed thence a short distance into Ywataung. Here the line divided, one branch winding west over the Mu River to Monywa on the Chindwin and northward to Yeu. The main line continued from Ywataung north through Shwebo to Naba, where a short spur joined it to Katha on the Irrawaddy. Beyond Naba the line passed through Mogaung and thence to Myitkyina on the Irrawaddy.26
Frequently touching chief waterways, the Sittang, Irrawaddy, and Chindwin rivers, and winding throughout the central basin, the railway net provided a great variety of widely dispersed potential targets. Rangoon, Thanbyuzyat, Pegu, Henzada, Pyinmana, Thazi, Letpadan, Paleik, Mandalay, Ywataung, and Naba were railroad junctions where rolling stock might be found in sufficient number to justify bombing attacks. Prome, Bassein, Moulmein, Martaban, Myingyan, Mandalay, Monywa, Katha, Mogaung, and Myitkyina were points where the rail and river traffic systems joined. Here were likely to be found docks, switching yards, and warehouses. Scattered along the many spurs were industrial centers such as Toungoo, Meiktila, Maymyo, Shwebo, and Yamethin. A few river ports, Bhamo, Magwe, Yenangyaung, Pakokku, Thayetmyo, and Allanmyo, also had industrial areas of some importance. Towns like Lashio, Myitkyina, and Yeu, terminals of certain lines, contained warehouses where goods being transferred to other means of transportation were stored.27
Aside from depots, marshalling yards, warehouses, and rolling stock, the railways offered numerous bridge targets whose elimination would go far in disrupting the flow of supplies through Burma. Ava bridge across the Irrawaddy near Mandalay and the Sittang River bridge on the Pegu-Moulmein track had not yet been repaired after British demolition, but several others were so strategically located that they were naturally earmarked for the earliest possible destruction. On the Rangoon-Mandalay trunk line, Pazundaung bridge south of Pegu and Myitnge bridge over which all goods from the south funneled into Mandalay were important control points. The Mu River bridge presented the most likely target on the Yeu branch. On the Lashio line the Gokteik viaduct, frequently called the engineering marvel of Burma, spanned an enormous gorge. As by-pass bridges and ferries were out of the question at that point, elimination of the viaduct would break rail connections to Lashio. This would have been doubly effective, for in addition to carrying practically all supplies to the Salween front, this line bore the products of the important mines in the Namtu area.28 These four bridges, Pazundaung, Myitnge, Mu, and Gokteik, were destined to receive many bomb showers.
Thus in Burma there were two phases of enemy transport offering strategic objectives to the bombers. The first included the movement by sea and the landing, processing, and transshipment of goods from the coast. To interfere with these activities became the chief objective
of the heavy bombers of the Tenth. The second phase was movement of materiel over the interior transportation system from the port of entry to troops in the field. Both heavy and medium bombers ran many missions to break this flow of supplies, the mediums being confined by lack of range to targets in central Burma and the heavies concentrating largely on southern Burma.
Rangoon, Bangkok, Moulmein, Tavoy, Mergui, Singapore, Saigon, and other coastal towns served as ports of entry for the Japanese in southeast Asia, but only Rangoon was both located within operational range and linked closely enough with the internal transport system of Burma to become a regular bombardment objective.29 Hence, it was to Rangoon and over its water approaches that most of the heavy bomber missions of the Tenth were flown. But because of the great distance involved, unpredictable weather in the Andaman Sea, and paucity of intelligence on movement of enemy bottoms, American bombers had not stopped goods from moving in and out of Rangoon. At the beginning of 1943, Tenth Air Force intelligence estimated that 30,000 to 40,000 tons of shipping passed weekly along the Rangoon River.30 Thus far the Japanese had not reconditioned the oil fields of Burma, so that an important part of this tonnage consisted of gas and oil for the air units in Burma.* Denial of this port therefore could curtail all types of military operations, but would be particularly damaging to the enemy air effort.
For some months the Tenth had desired to supplement sea searches and bombing of dock installations by mining the Rangoon River, but it was not until January 1943 that the air force obtained suitable mines and necessary technical assistance. Mines and information as to moon phases, tides, and the harbor channels were obtained from the RAF, and after coordination with the commander of the Eastern Fleet of the Royal Navy and other British authorities, mining operations began. Liberators were modified to carry the mines. Selecting a time when there would be a low tide and full moon, and accompanied by a diversionary mission over Mingaladon and Rangoon, the B-24's dropped forty magnetic mines in the Rangoon estuary on 22 February.31 Mining became a more or less regular routine for the remainder of the year.32 No information was available on the number of ships actually sunk as a result of the mine-laying missions, but it was certain that the enemy
* Later in 1943, when the Japanese began serious work on the oil fields at Chauk and Yenangyaung, a series of bombing missions was run against those targets.
was kept busy sweeping the river and that the number of ships docking at Rangoon was drastically reduced.
Liberators also struck at rail targets, largely in the area south of Thazi, although they occasionally lent aid to the B-25's which assumed responsibility for rail targets in central Burma. Toungoo, Pyinmana, Yamethin, Prome, Pyawbwe, Letpadan, and Henzada were the most important targets attacked on the rail system. Pazundaung bridge also received considerable attention from the B-25's.33
In central Burma the Liberators hit Ywataung rail yards and Monywa on 22 June and struck Mandalay on 20 July and 1 September. A second strike at Monywa on 19 September was followed the next day by a mission to Sagaing and another to Naba on the Mandalay-Myitkyina line. The latter was the northernmost point hit by the Liberators during the year. In October, Sagaing and Myingyan were hit once and Kanbalu twice. On 17 October, Liberators collaborated with Mitchells to give Naba a thorough going-over, and on 30 December twenty B-24's almost completely knocked out Monywa.34
Among the bridges which the heavy bombers attempted to destroy were Sinthe, Myitnge (and Myittha just to the south), Meza, Gokteik, and Shweli. Some damage was done to nearly all these targets, but always the Japanese were able to make them usable in a short time.35 Because of its peculiarly strategic location, Myitnge was the most frequently visited bridge target. On the ten occasions when the heavies bombed it, they could claim only superficial damage. One of the most interesting, and perhaps most desperate, attacks on this vital structure was a minimum-altitude attack by two old B-17's which had only recently been made flyable after many months of inactivity. This experimental mission, too, brought no success.36
Sea searches continued throughout 1943 but with questionable results. Undertaken as the first effort to cut off supplies from Burma in 1942, the activity eventually became only a supplement to the heavier effort to knock out port facilities and close Rangoon by mining.37 The water expanse of the Andaman Sea was too great for anything approaching complete coverage by the limited force available, so that missions were in reality reconnaissance sorties sent out on the chance that enemy surface craft might be located. Should a convoy be spotted, additional aircraft could be directed to attack. Many of these sorties were thwarted by weather which provided cover under which Japanese ships could reach their destinations undiscovered. But in spite of
the many flights which clouds and fogs made fruitless, the chance of sighting enemy craft was better in monsoon weather than in clear periods, for when they had no protection from clouds the Japanese stayed outside the range of the B-24's, hugging the Malay coast and moving only at night. Yet the regular sweeps over open sea were not entirely fruitless. Experiments with radar equipment were carried on with enough success to promise great rewards when sufficient radar-equipped aircraft were obtained. Furthermore, it was customary for planes returning from unsuccessful searches to fly over points in southern Burma where alternate targets had been selected. Several times they did heavy damage to enemy installations on these return missions.38
Aside from shipping, all strategic targets worthy of attack by, and in range of, the B-24's lay in the vicinity of Rangoon, and the weightiest effort of the 7th Group was directed at objectives in that region. The distance flown by American aircraft on these missions was greater than that required for planes based in Britain to strike Berlin, but it had long been a "milk-run" for India-based Liberators. Moreover, the Japanese had built up their AA defenses at Rangoon until that city became one of the most heavily fortified areas in all southeast Asia. Heavy antiaircraft and batteries of searchlights were concentrated at vital points, while the larger part of enemy fighter strength in Burma was based at Mingaladon and other near-by airdromes. A majority of missions to Rangoon therefore met resistance, and as the Tenth had no long-range fighters until arrival of P-38's and P-51's late in 1943, all missions were flown without escort. Once the enemy discovered that the current-model B-24 lacked adequate defense against frontal attack, he exacted an alarming toll. In October, B-24J's with better frontal firepower arrived, but these new planes with their front turrets were a distinct disappointment in early operations. Over Rangoon on 1 December they suffered heavy losses from frontal attacks. Inexperience in handling the new turrets was given as a possible explanation of the losses. But in spite of serious handicaps, the Liberators flew many successful daylight missions and brought damage to Rangoon.
From the first of 1943 until the monsoon closed in, heavy bombers attacked key targets in the Rangoon sector with some degree of regularity. Several of the most frequently bombed objectives during this period received priority in the program of rendering the city useless as a port and storage area for materials awaiting shipment to the interior. Among these were ships anchored at docks, the docks
themselves, and adjoining warehouses. As part of the general plan for upsetting the land transportation system the Central Railway Station, Mahlwagon roundhouse and rail yards, and the Pazundaung railway bridge were given a generous showering of bombs. Destruction of Pazundaung bridge would have delayed all rail traffic northward to Mandalay, but the bombers were able to do no more than make it unserviceable for short periods. Damage to railway repair facilities and trackage at Mahlwagon yards and Central Station probably was more vexing to the occupying forces. Other heavily bombed targets prior to the monsoon were Syriam oil refineries, Thilawa oil storage area, and the large airdrome at Mingaladon.39
Rain and fog cut down the number of missions to Rangoon during the summer, but in July, weather permitted a flight to bomb Syriam refineries, and in September both the refineries and Sule Pagoda docks and storage area were bombed. With better weather in October regular missions were resumed. Just before the combined effort of the Tenth and Fourteenth Air Forces and the RAF to give Rangoon a knockout blow in late November and early December 1943, Liberators visited the most important fields where interceptors might be based, dropping heavy loads of bombs.40
When General Stratemeyer arrived in the theater he was eager to promote closer cooperation between the AAF and RAF, and in November he projected one of the most significant series of missions ever executed in the CBI theater. He proposed to Air Chief Marshal Peirse that the two air arms collaborate in a series of attacks intended to destroy completely the most vital installations in the Rangoon vicinity. Possibly influenced by the danger of attacks on Calcutta and the Assam line of communications by a growing enemy air force in southern Burma, Peirse readily agreed. Stratemeyer then proposed to Chennault that the air echelon of the 308th Bombardment Group be temporarily moved to India to add weight to the effort. Heavy bombers in China at that time were hamstrung by shortage of gas, and one advantage of participation in the missions was that their return to China could be utilized as a ferry mission. Moreover, destruction of any considerable part of enemy air strength in Burma might relieve pressure on the air ferry across the Hump and forestall any impending air attacks on Assam where stores for the Fourteenth were massed.41 Chennault agreed to the transfer.42
The operational procedure was to be worked out by the Bengal
Command and Tenth Air Force, from whose bases all aircraft would operate. After giving close study to damage resulting from previous bombings, specific targets were given a tentative priority.43 Only a limited number of targets could be designated and hence great care was given to their selection. The locomotive works at Insein stood out as probably the most remunerative target in the region and was eventually given top priority. Strafing and bombing along the railways had done considerable damage to locomotives, placing a strain on workshops, and Insein was the only place in Burma having necessary machinery for repairs to railway engines. Elimination of this single plant therefore would supplement the continuing campaign against rail transport. Railway stations were passed over as being too hard to hit and to damage permanently. Mahlwagon marshalling yards and engine sheds were selected as good night targets, easily spotted because of their distinctive position between two bends in the river. Docks at Rangoon had always been considered lucrative targets by the Tenth, and its bombers had flown some very successful missions against them, though never with a decisive weight of attack. This was an opportunity to cripple the whole water front at one time, so in addition to the Insein locomotive works and Mahlwagon marshalling yards, the wharves were chosen as a third major objective.44
All attacks by night were to be flown by Wellingtons and Liberators of the RAF, and all AAF missions were to be flown by day. Thus there was collaboration between the two forces, but no integration on specific missions. Heretofore all American bombardment missions in the area had been flown without escort, but as the projected attacks constituted an outright challenge to the increasing Japanese air power in Burma it was thought advisable to provide escorts. Preliminary plans were laid with the assumption that the only fighters available would be the recently arrived P-38's of the 459th Squadron. At the last moment, however, the 530th Fighter-Bomber Squadron brought its P-51's from Assam to aid the P-38's.45
The 490th Bombardment Squadron (M) was to participate in the attacks along with the heavy bombers of the 308th and 7th Groups. When the flight echelon of the 308th arrived, half of it went to Pandaveswar and half to Panagarh where the 7th Group was located, giving each base two squadrons from each group. Thus the ground men of the 7th could give the 308th aid in maintenance.46 Arrangement for the fighters and mediums was not so easy. Neither had sufficient range to
make the flight from their base at Kurmitola, so forward staging fields had to be used. It was decided that the medium squadron would stage at Chittagong, 485 miles from Rangoon, and the fighters at Ramu, near Cox's Bazar and 430 miles from Rangoon. A number of 750-gallon refueling trucks were sent to the staging areas to service the aircraft.47 Fighters, of course, were equipped with belly tanks.
The operational plan adopted was as follows: on D-day, 25 November, the maximum strength of B-24 and B-25 aircraft of the AAF, escorted by the fighters, was to attack in two waves. The 7th Group, forming the first wave, was to hit Insein locomotive shops; the 308th Group and 490th Squadron, or second wave, would bomb fighter fields in hope of destroying aircraft on the ground, including fighters being reserviced after they had intercepted the first wave. That night, maximum strength of RAF bombers would attack Mahlwagon marshalling yards, with the AAF following up with an attack on the same target the next day. Beginning the night of D plus one, the RAF and AAF would strike by night and day against the wharves, starting at Ahlone wharves and moving east on each successive raid. The whole series of missions, including those on Insein and Mahlwagon, was expected to last six days and five nights. It might be necessary to divert part of the daylight effort against airfields if results of the first attack were not adequate. On approximately D plus 8 the AAF was to mine the shipping lanes at Rangoon and Moulmein. Exact timing of these mining missions would be governed by the moon phase should they be undertaken at night.48
Weather was entirely unfavorable on 25 November when the combined operation was supposed to begin, but as the 308th would be in India for only a short time it was believed best that the set schedule be followed. Misfortune set in from the take-off of the first mission when two B-24's crashed, killing all on board. When the heavies passed the point at which they were to pick up their escort from Ramu, overcast prevented the fighters from making contact, leaving the bomber formation to proceed to the target alone. The primary target at Insein was completely closed in by weather and the first wave was unable to attack. The second wave encountered the same conditions at its Mingaladon objective, and this second major target also was abandoned. While circling to find an opening through the overcast one B-24 sustained a flak hit which later caused it to crash. On the return some of
the bombers hit Akyab airdromes with indifferent or undetermined results.49
The only part of the first day's task to be accomplished was performed later by the 490th Squadron accompanied by P-51's of the 530th Squadron. Flying at lower altitudes than the heavies, the B-25's bombed Mingaladon with some success. Damage was done to buildings and the revetment area, and two aircraft were believed to have been destroyed on the ground. Enemy fighters rose to intercept, and in the ensuing battle the P-51's claimed one enemy aircraft destroyed and four probably destroyed. Two P-51's were shot down and two others damaged. Gunners on the Mitchells shot down one plane, damaged two, and claimed three as probables, the mediums escaping without damage.50
The result of the initial effort was extremely disappointing. Three heavy bombers and two fighters were lost and the major target at Insein was untouched. Nor was the anticipated blow at enemy air power successful. Furthermore, the element of surprise, heavily depended upon to cripple enemy interception for succeeding missions, was gone; the general schedule of missions was upset and plans had to be revised. The Japanese were now well aware that two heavy groups were operating from India; the enemy would be on the alert for double blows such as were planned for the first attack, and would probably offer a determined resistance.
On 26 November all flights were called off because of weather. With two days gone and nothing accomplished, the planned schedule was thrown aside, and on the 27th, AAF Liberators accompanied by Lightnings, and Mitchells escorted by Mustangs, struck at Insein. Despite determined interception by a large number of enemy fighters just prior to the bomb run, results of the attack were excellent. In a subsequent report General Davidson, in command of the Tenth Air Force since August, estimated that at least 70 per cent of the buildings and installations of the locomotive works were destroyed.51 In the aerial fight which developed from the interception, Japanese pilots pressed their attacks home time after time. After the mission returned, it was found that four P-51's, two P-38's, and three B-24's had been lost. One of the Mustangs shot down was piloted by Colonel Melton, commander of the 311th Group, who was seen to bail out and land in territory where natives were generally friendly. One of the B-24's landed in water off the coast and nine of the crew were rescued. Thirteen enemy fighters
were claimed destroyed, seven probably destroyed, and four others damaged.52
An attack on Botataung docks was set for the following day, the 28th. Since the provision of escort for B-24's at approximately 18,000 feet and mediums operating at about 9,000 feet was too great an undertaking for the few fighters left, the mediums on that day attacked Sagaing instead of flying with the heavies to Rangoon. Over the targets the Liberators encountered far less resistance than on the preceding day and no American aircraft was lost. Four interceptors were shot down and five more claimed as probables. Heavy damage was done to the dock area and results of the mission were considered very good.53
The 29th and 30th of November were set aside for maintenance, but on 1 December the B-24's revisited Insein while the B-25's bombed Myitnge bridge. All available fighters, now only ten P-51's and fifteen P-38's, were assigned as escorts to Insein. Delayed in taking off from Kurmitola by heavy fog and unable because of poor communications to warn the bombers, the P-51's failed to finish refueling at Ramu in time to make the rendezvous. The mission went out with only the fifteen P-38's to protect it.54
Japanese fighter strength in the Rangoon area apparently had been at a low ebb on 28 November, but in the two intervening days they must have brought in heavy reinforcements from neighboring regions. When the bombers made their run from north to south in order to avoid heavy antiaircraft fire, the sixty-odd enemy fighters already aloft were able to make head-on attacks out of the sun. The first assault was as devastating as it was surprising. Enemy aircraft were in firing distance before they were sighted, concentrating on the formation leaders. The 7th Group, forming the first wave, bore the brunt of the attack. On the first pass the group leader, his left wingman, and a squadron leader were knocked out. Three planes pulled up to close the gaps in the formation and soon afterward one of the three was lost. Three others tried to cover the group leader, who was losing speed and altitude, and thus did not complete the bomb run. The P-38's could give little direct assistance, as they had their hands full with other fighters still above the bomber formation.55
When the planes of the 308th Group arrived and were ready to begin their bomb run, the attacks were repeated by a slightly smaller number of aircraft. Sometimes enemy fighters came in three abreast, all concentrating on a single plane. At other times they approached in a
string, each plane making a pass and pulling away to allow the next in line to come in. The lead plane of the 308th was shot down on the first pass, just before the bomb run, and the plane which took its place was badly hit during the run. Attacks persisted after bombs were away, enemy pilots singling out cripples; but the P-51's finally arrived in time to offer some protection on the return, losing one ship in their brief participation.56
Bombing results of the costly mission were largely unobserved because of the continuing fighter attacks during the bomb run, but the pattern was believed good. American losses, however, were appallingly high--six B-24's and one P-51 destroyed and five B-24's seriously damaged.57
The American phase of the operation came to a close on the afternoon of 4 December when AAF bombers ran successful mining missions to Rangoon and Moulmein without encountering resistance or suffering losses. The AAF missions on 25, 27, and 28 November and 1 December resulted in the loss of twelve B-24's, eight P-51's, and two P-38's, while many other craft of various types were temporarily unusable because of damage sustained.58
Meanwhile RAF missions were flown on the night of 28 November against Insein, and on the night of the 30th against Mingaladon and Zayatkwin airdromes and the Rangoon dock area. After the last bombing effort of the AAF on 1 December, the RAF flew night missions on 2, 5, and 6 December, striking at Bassein, Heho airdrome, and Moulmein. Its forces on all these missions were relatively small, and in all only sixty-six sorties were flown at the expense of three Wellingtons.59
The many factors involved make it almost impossible to reach an objective evaluation of these combined missions. Due to the limited time the 308th Group was available the plan could not be flexible in timing, and when bad weather intervened, the alternatives were either to call the whole operation off or try to carry it out in the face of undesirable flight conditions. Once the element of surprise was taken away by an abortive mission, each succeeding mission was more risky. It must be remembered, however, that on all previous missions the Liberators had flown to Rangoon without escort and without heavy losses from fighters. Hence it was not unreasonable to expect that the small escort provided would be sufficient to minimize losses from hostile aircraft.
The operation was an expensive one in a small air force where loss of every plane was felt. Reckoning on a percentage basis, on the other
hand, the loss was less alarming. While serious, loss of eight P-51's in a series of some sixty sorties where interceptors were numerous and very determined was not unreasonably high. The rate of loss among B-24's was even lower--twelve in 205 sorties. Only on the mission of 1 December did heavy bomber losses exceed 10 per cent of the participants.60
The objectives of the operation were not fully accomplished. Serious damage was done in the dock area, but it was not so extensive as to paralyze the water front. Enemy aircraft losses were probably upwards of fifty; but owing to arrival of reinforcements during the operation, Japanese air strength was greater at the finish than on the first day. Some damage was done to major enemy airfields in southern Burma. Communications targets such as Mahlwagon marshalling yards were not attacked.
On the credit side of the ledger were the great destruction at Insein and a very successful mining mission which affected both Moulmein and Rangoon. Photo intelligence as well as ground intelligence coming in later indicated that in the face of limited successes elsewhere destruction at Insein alone might have justified the whole undertaking. Several vital parts of the locomotive works were completely obliterated and many others were so badly battered as to be utterly useless. A Tenth Air Force photo intelligence report of 1 December stated: "The functional capacities of the Locomotive Work Shops have been seriously and effectively checked. The complete destruction of certain vital departmentsÉ makes it extremely doubtful whether this Works will be able to operate for a considerable time."61
Less tangible results are not easy to assess, but the fact that RAF, Tenth Air Force, and Fourteenth Air Force units had participated in a jointly planned series of missions was a good omen for the theater. British effort was smaller than anticipated, consisting of only sixty-six sorties instead of the anticipated maximum of some 175. Cooperation between the 7th and 308th Groups was beyond reproach.62
Several important operational lessons were learned which would be of value in planning for the future. Staging medium bombers from Chittagong and fighters from Ramu was entirely feasible, but it was believed that in subsequent operations the fighters should arrive at the staging fields the night before the mission, thus permitting a refueling in ample time to make the rendezvous with the bomber formations. Both P-38's and P-51's showed their value as escorts, but the P-51 with
greater belly-tank load per engine was better for close support, while the P-38 was superior as high-altitude top cover. Gunners on fighters and bombers were stale and needed additional training. And, perhaps most significant of all, fighter escorts would probably be required for all subsequent daylight missions to Rangoon.63
After this series of attacks, Rangoon was left alone for a few weeks, but meanwhile the potentialities of another target had greatly increased. Throughout the year intelligence agents had reported that the Japanese were expanding docking facilities at Bangkok and building a railway to connect this port with the Ye-Moulmein railway, and thus to the railway system of all Burma. In December its reported completion made Bangkok an increasingly important bombardment objective in the Burma campaign. A year before, B-24's of the India Air Task Force had flown to this port and dropped a few bombs, and in April another such mission had been attempted. On this latter mission most of the planes failed to reach the target, and those which succeeded in dropping bombs did little appreciable damage.64
On the night of 19 December, twenty-one B-24J's of the 7th Group took off to bomb the newly expanded Bangkok dock area. One failed to reach the target, but shortly after midnight the remaining Liberators began to rain their bombs on the water front. Some of the heavies were singled out by searchlights which followed them through their bomb runs, blinding crew members so that they could not assess the accuracy of their bombardment. Flak was ineffective and no interceptors appeared. For more than an hour the various flights dumped their bombs, most of which were believed to have fallen within the assigned target area. In all they dropped 100 X 500-pound bombs, but mechanical failure of bomb racks caused them to withhold ten incendiary clusters. Although no fires were reported, it was thought that substantial destruction had been wrought.65
On the night of 23 December a second attack was made on Bangkok, this time with the railway terminal as the aiming point. Twenty-one Liberators took off, with two aborting. The remaining nineteen scattered upon the target 110 X 500-pounders, of which fifty-nine were incendiaries. Upon this occasion there was no doubt that the chosen objective was hit effectively. All squadrons sighted huge fires, and one reported heavy explosions three minutes after the bomb run. Again flak was not effective, and the two enemy aircraft sighted failed to attack.66
These two Bangkok missions did much to raise morale of the 7th Group after its heavy losses at Rangoon. Two successful fourteen-hour night missions had been flown within a four-day span, with only three abortive sorties and without loss of a single ship. Bangkok and the Bangkok-Moulmein railway were destined to be important objectives for the Tenth during the coming year.
Medium Bomber Operations in Central Burma
While heavy bombers of the 7th Group concentrated on the more distant targets, B-25's of the 22d, 490th, and 491st Squadrons of the 341st Group carried out a second phase of the interdiction program by attacking the enemy's communications farther north. Enemy airdromes, whenever they were found to be occupied, also received attention. Governed by the limited range of their aircraft, these squadrons concentrated on the Mandalay region of central Burma, operating in the general area between Thazi and Myitkyina.*
Nature was kinder to the pilots of these mediums than to fighter pilots in Assam or to the heavy squadrons in the south, for even during the summer monsoon the dry area in middle Burma was not closed over by the mists and fogs so characteristic during the season on the southern coast and in northern Burma and Assam. Consequently their missions were less frequently abortive, and they could adhere rather closely to operational plans. Nor did they encounter objectives so well defended by antiaircraft batteries and enemy interceptors as at Rangoon, or so well concealed as those in the northern area.67
Nevertheless, the 341st Group had its share of operational problems. Objectives were widely scattered though lightly defended, and few were large enough to allow area bombing. As a result a very high degree of precision was required on practically every mission. Furthermore, when an objective was of such proportions as to justify area attacks, the medium force was too small to saturate the target in a single mission.68 Two consecutive missions to the same place frequently resulted in the same portion of the area being twice blanketed while other parts remained entirely untouched. But nothing caused more headaches among medium crews engaged in transportation interdiction than the difficulties of "bridge-busting." Try as they might, the
* In May the 490th moved to Kurmitola, where it could operate without dependence on a forward staging field. The other two squadrons, however, continued to use staging fields.
percentage of hits on these narrow targets remained pitifully low; and if they were difficult to hit, they were infinitely more difficult to destroy. Experimentation throughout 1943 on methods of approach, altitude of bomb release, and bomb fuzing failed to produce a suitable method of attack, and destruction of a bridge was more or less the result of luck.69
On top of the technical problems involved in pinpointing these small targets, crews were confronted with several ingenious devices which the Japanese used to multiply the complexities of that type of operation. In some instances, smoke pots were installed so that the target could be screened; if no natural barriers hindered minimum-altitude approach, heavy concentrations of antiaircraft were strategically placed; in some instances where bridges spanned deep gorges, cables were strung across the gorges to stop approaches at or below bridge level. Flak positions were shifted frequently, and when antiaircraft guns were scarce, attempts were made to outguess the bombers by concentrating the guns at the next probable objective.70
Three types of internal transportation were of enough importance to justify consideration - river, rail, and motor. The central dry region contained control points of northbound traffic over all three systems. Destruction of river craft by the British during their 1942 retreat, however, had been far more extensive than destruction of railways, locomotives, and rolling stock, and the volume of goods moving along waterways had dropped off considerably during Japanese occupation. Since RAF aircraft had assumed the role of destroying all types of river craft plying the Irrawaddy and Chindwin, attacks on river traffic by American bombers were infrequent.71 When other targets were closed over, however, the mediums sometimes ran river sweeps, attacking tugs, barges, and ferry boats. Once during the summer they planted magnetic mines in the Irrawaddy for a stretch of fifty miles, but with questionable results. Motor transport in general also provided few targets appropriate for medium bombers. Consequently, efforts to interfere with motor traffic most often took the form of bombing motor pools, strategically located highway bridges, and cuts in highways where landslides might be caused. In a few instances motor convoys were bombed and strafed.72 But the main targets lay along the rail system from Rangoon to Mandalay and Myitkyina which served as the main supply artery of the Japanese armies in Burma.
Had a large force of the proper type of aircraft been available,
interference with rail transportation in middle Burma would have been a minor undertaking, but the Tenth Air Force had neither sufficient strength nor the various types of aircraft needed for the operation. Instead, only three undermanned B-25 squadrons were assigned to the task, and before the end of the year this force was to be reduced to a single squadron. The only reinforcement was the 459th Squadron (P-38) which operated in the same area in the autumn. Blowing up bridges, ripping out trackage, burning stations, blocking tunnel entrances, destroying workshops and roundhouses, and causing landslides in deep cuts gave promise of favorable returns, and all were tried with varying degrees of success. But the Japanese became amazingly adept at making repairs and unsnarling traffic. Hence it was ultimately recognized that these methods were achieving little permanent damage, and that only by destroying locomotives and rolling stock could progressive and cumulative dividends be realized. This was no small undertaking. It was estimated that 113 locomotives and 9,602 rail cars of all types were available to the enemy. They were practically irreplaceable, however, and although it would take months to make appreciable inroads into the supply, the mediums accepted this part of their assignment with alacrity.73
So-called marshalling yards in Burma frequently were merely storage areas for idle locomotives and rolling stock. It was here then that chances were best for wiping out railway equipment. Juxtaposition of rail yards and warehouses gave frequent opportunities for double destruction; and if yards were clear of rolling stock, the storage areas were excellent alternate targets. At a few points docks adjoined switching yards, again making better the chances for material destruction. On rare occasions bomb damage to bridges caused congestion of traffic and made normally poor targets into profitable ones.
Consequently, although the Mitchells of the 341st bombed bridges, barracks, and other enemy installations, their heaviest and most rewarding effort was against rail centers and storage areas. Guided by day-to-day information provided by reconnaissance pilots and intelligence agents in Japanese-held territory, they attacked wherever concentrations of rolling stock were reported. Striking as near to the source of supply as range permitted, they bombed Thazi no less than twenty-two times from late March to 1 October, the missions totaling 179 sorties. Against Kyaukse, Myingyan, Pyawbwe, and Meiktila, all of which are also south of Mandalay, they flew more than 175 sorties
during the year. Over a dozen missions of approximately 100 sorties attacked Mandalay itself, but as antiaircraft there was perhaps the heaviest in central Burma it was believed more desirable to strike other objectives in the immediate vicinity. On the Lashio road, Sedaw reversing station and Maymyo were attacked seven and fifteen times, respectively.74
Beyond Mandalay the Mitchells gave Sagaing and Ywataung rail yards the most severe treatment of all. Some 240 planes in 23 missions showered their explosives on the tracks over which were moving heavy shipments to the northern battle area. Farther up, Monywa on the Yeu branch suffered five attacks, while on the main line Kanbalu, Naba, and Shwebo were hit hard and often. Dozens of other points along the tracks were also blasted, some as alternates when assigned targets were closed over.75
Interspersed with these heavier attacks were lighter ones against trains and against cranes and other repair equipment and repair crews. When the newer model B-25's equipped with 75-mm. guns appeared late in the year, they were sometimes used to knock out strategically located flak emplacements. Any locomotive caught outside defended areas was subjected to strafings.76
For many months the Japanese proved a worthy foe in the transportation contest; repairs were prompt and thorough. But as the attacks became more frequent and devastating, reconstruction lagged. Burned-out rolling stock, wrecked locomotives, and bomb-pitted sidings remained untouched for long periods while workers made feverish efforts to keep main lines open. As the tide slowly turned against him, the enemy became more wary and depended heavily upon guile. Camouflage and dispersal became his guiding principles. Locomotives were disguised as box cars and placed in the middle of trains; cars on sidings were uncoupled and well-spaced revetments were constructed to protect locomotives when not in use; massing of rolling stock was avoided whenever possible; trains rarely made runs during daylight hours.77 Against these precautions medium bomber missions became less fruitful, but efficiency of the railways also diminished. Accumulated combat mission and photo reconnaissance reports telling of explosions, riddled locomotives, burned warehouses, and wrecked rolling stock indicated that heavy damage was being done.
The medium bomber campaign against railroads was severely curbed, however, when in October two of the three squadrons, the 22d and
491st, were alerted for transfer to China. Though the move did not actually take place until late December, the two squadrons flew practically no combat missions during the last two months of the year. The effect of their imminent transfer was only partially offset by the greater proficiency of the P-38's in their cooperation with the Mitchells and by the fact that Liberators of the 7th Group began to run a few missions to central Burma.78
Meanwhile, attacks on bridges, a special responsibility of the 341st Group, had failed to keep pace with the destruction of rail centers. Although there were in Burma nearly a hundred bridges of a length of 200 feet or more, certain considerations made the selection of those to be attacked comparatively easy.79 Pazundaung, Sittang, and Sinthe were out of range. Ava was still in a state of disrepair. In the Myitkyina area several important bridges were within range of fighter-bombers from Assam, where crews had developed their own effective methods for bridge destruction.* Myitnge, Gokteik, Mu, Meza, and Myittha railway bridges, together with the Shweli highway bridge on the road from Bhamo into China, were the logical targets for the Mitchells.80
All the difficulties of the bridge campaign in Burma during 1943 are illustrated in the story of attacks on one bridge--Myitnge. Located just south of Mandalay, this four-span, truss-type, steel structure bore all rail traffic from the south into that city. The demoralizing effect to be expected from its destruction was obvious, and aside from Rangoon, it became the most bombed target in Burma. On 10 January 1943 the bridge was reported "destroyed"; but later reconnaissance showed that while damaged and unserviceable, it was far from irreparable, and in early February B-25's and B-24's collaborated in a series of missions designed to place it beyond repair. On 4 February, six Mitchells bombing from 6,000 to 6,500 feet and seven Liberators from 14,500 feet accomplished only slight damage to the south approach. The following day six more B-25 sorties at 12,000 feet failed to smash the bridge. Heavy bombers on 6 and 12 February had no better luck, on the latter occasion claiming twenty-three hits in the target area but doing the main structure no appreciable harm. The attacks continued on 14, 15, and 23 February, and on the latter date the Liberators battered the roadbed and tracks on the south approach.81 From 8 to 18 March the 341st Group ran six missions of fifty-three sorties, releasing bombs at altitudes varying from 1,000 to 16,000 feet without doing visible
* See above, pp. 464-65.
damage. On 19 March, eight Mitchells scored at least four direct hits, rendering the bridge temporarily unserviceable. This, however, did not deter the bombers in their efforts to destroy the structure completely. Heavies of the 7th Group attacked in full strength on 24 March but made no hits. The same day two B-17's, flying over the target at fifty feet, dropped four 1,000-pounders without effect.82
Throughout April, May, and June the attacks continued, mediums scoring four hits on 17 April and two on 15 June. On 3 July the southernmost of the four spans was knocked from the piers into the riverbed, but regular attacks continued until 23 August, when Mitchells knocked out one of the two center spans and heavily damaged two others. No further attacks were made until 1 December, when the 490th was diverted from the Rangoon missions to hit the newly repaired structure. Two direct hits seriously damaged the northernmost span, and again the bridge was unserviceable. Two more attacks in December, however, indicated that regardless of its temporary uselessness the bridge remained high on the target-priority list, and on 1 January 1944 the bridge was again in use.83
These 1943 Myitnge bridge attacks left the basic problems of bridge destruction still unsolved. Successful B-25 attacks had been accomplished from 6,200 to 13,500 feet, with varying formations, aiming points, and angles of approach; but unsuccessful missions still overwhelmingly outnumbered successful ones.84 Cumulative statistics on this target indicate the failure of bridge bombardment from medium and high altitudes. In 39 missions of 337 sorties, Liberators and Mitchells dropped 1,219 bombs (542.8 tons), registering 18 hits on the bridge - an accuracy score of a little less than 1.5 per cent. The record of the B-25's, however, was far better than that of the B-24's, for the latter scored only 1 hit in 81 sorties while B-25's made 17 hits in 254 sorties.85
Antiaircraft was regularly encountered over Myitnge but was relatively ineffective. Two B-24's were shot down there and two others damaged, but no Mitchells were destroyed and only eight were damaged. Enemy aircraft encountered on three occasions inflicted no injury on any of the bombers. On the other hand, the constant showering of explosives had not wrought any permanent damage to the bridge. All piers were still intact at the end of the year, and as long as they stood, repairs were relatively simple. Hence the only material value of the campaign lay in the fact that for perhaps two-thirds of the year the bridge was partially or entirely unserviceable.86
Gokteik viaduct was probably the second most important bridge target of the Tenth Air Force. Built by American engineers in 1900-1901, this structure across a gorge 2,260 feet wide was mounted upon latticed steel piers rising 320 feet from a natural bridge which spanned a small stream 550 feet below. Thus the over-all height of the bridge platform from the bottom of the gorge was 870 feet. On the north side the railway entered a tunnel only a short distance from the end of the bridge.87 Reconstruction of this span or unblocking the tunnel entrance would present major engineering problems which might induce the Japanese to abandon the rail line stretching beyond. This line was doubly important, for besides carrying supplies from Mandalay to Lashio for the Salween army, on the return it hauled from Bawdwin mines and Nanitu smelters lead and zinc, critical items in Japanese war economy.88
Upon reported destruction of Myitnge bridge early in 1943, American strategists made plans for dealing out similar treatment to Gokteik. Because of the problem of reconstruction after the war, the British at first were reluctant to grant permission to bomb this objective, but when it was pointed out that the enemy undoubtedly would destroy it before he withdrew from Burma, they finally consented.89 On 20 February mediums failed to score on the target. Four Mitchell missions of forty-two sorties and one Liberator mission of fourteen sorties during March were equally ineffectual.90 After a letup of more than a month eighteen Mitchells on 30 April claimed minor damage at the north end. No attacks took place during the summer months, but on 7, 8, and 10 September the mediums again ran missions against the viaduct. On 7 September three hits at the base and two or three near misses on one pier did minor damage but left the viaduct and approaches intact. Five hits at the base on the 8th and direct hits on approaches on the 10th further damaged the structure but still did not make it unusable. Plans for the move of the two squadrons to the Fourteenth Air Force* so curtailed activities of the Mitchells during the remaining months of 1943 that no further attacks were made on Gokteik. Like Myitnge, this structure was intact at the end of the year.91
On the Mandalay-Myitkyina line the Meza railway bridge, just below Naba, was another important target over which Japanese reinforcements poured into northern Burma. This 700-foot, three-span, truss-type bridge with five short approach spans at each end was
* See above, pp. 487-88.
mounted on concrete and brick masonry abutments. It was attacked less frequently but more successfully than either Myitnge or Gokteik. The first 1943 attack was made by nine Mitchells on 13 June, when one hit did minor damage. No further assaults were made until October. On 10 October seven Liberators in javelin formation at 8,000 feet made five hits with 1,000-pounders, destroying three eastern approach spans and dropping one end of a main span into the river. While repairs were still in progress, Mitchells attacked on 20, 23, and 31 October, straddling but missing the bridge on two occasions, yet doing serious damage to approaches. The bridge was unusable and no subsequent attacks took place during the remainder of the year.92
On 12 December, Myittha bridge, not attacked heretofore, was given a saturation bombardment by twenty-eight Mitchells and thirteen Liberators. This four-span, 240-foot structure had been adjudged by Tenth Air Force intelligence as one of the most important targets in Burma because of the volume of Japanese goods then flowing northward through that area. Five hits were claimed for the day, but later photo reconnaissance brought the sad news that the only damage was to the approach spans. Flak damaged one B-24 on this mission, but enemy interceptors encountered did the bombers no harm.93
The only highway bridge of enough importance to attract the attention of bombers during 1943 was Shweli, 250-foot, suspension-type structure seventy feet high, on the motor road between Bhamo and China. Shweli presented peculiar difficulties to the bombers, since direct hits on the platform would not cause heavy damage and the cables were so securely anchored in huge concrete blocks as to make it almost impossible to dislodge them. The towers over which the cables were strung were the most vulnerable parts, but making direct hits upon them was more than the bombardiers could accomplish. Attacks by heavy bombers on 31 April and 4 July and by mediums on 24 June were completely unsuccessful. On 19 July, B-25's damaged approaches, and on 1 August, in the last attack of the year, eight Mitchells hit the eastern approach, slightly damaging the cable anchorages and pylons but leaving the bridge usable.94
On the Yeu spur, a bridge of four 100-foot, steel-girder, deck-type spans crossed the Mu River between Ywataung and Monywa. This was the one bridge which was exclusively a B-25 target. On 7 April the mediums scored two direct hits and on 9 July registered two more, each attack temporarily knocking the bridge out. On 29 July two more
flights attacked. The first reported heavy damage to the two east spans; the second reported the bridge "destroyed," with the east span dropped and submerged in the river. By 22 September, however, the structure was again in use, and raids on that date and on 22 October failed to do any damage. These ended the 1943 assault on this particular target.95
A survey of attacks on the six major bridge targets in central Burma during the year shows how expensive the operation was, and also how ineffective. Against these bridges, Myitnge, Gokteik, Shweli, Meza, Mu, and Myittha, 696 sorties were run from 4 February through 31 December. During these missions 2,398 bombs, ranging from 300 pounds to a ton but mostly 500- and 1,000-pounders, were dropped. They totaled almost 1,100 tons and represented approximately 17 per cent of the bomb tonnage which fell on Burma during the period. Of the 2,398 bombs only 34 struck bridges, making accuracy less than 1.5 per cent. Actually, of the 1,100 tons of bombs, only 17 tons were effectively placed, and with the exception of Myitnge, none of the bridges were rendered useless for extended periods.96
Although the record of the mediums for accuracy was far poorer than that of the fighter-bombers from Assam, it was better than that of the B-24's, which were obviously misused in attacking bridges.97 Morale was lowered among the men of the 490th Squadron, which was left with the responsibility for bridge attacks when the 22d and 491st Squadrons were transferred to China, and they began to look with dread upon such missions. Lt. Col. Robert D. McCarten refused to be discouraged and instituted a training program to solve this problem. It was this program which eventually led to success. On 1 January 1944, Maj. Robert A. Erdin, pilot of the lead Mitchell bombing the Mu River bridge, discovered by accident the secret of successful bombing. Avoiding a tree on the bomb run, he dumped his bombs as he suddenly pulled up, and to his surprise they toppled two spans of the bridge into the river. Further tests in the training program proved that the correct method of angling the bombs had been found, and after refining this method of attack the 490th became so proficient as to merit the title "Burma Bridge Busters." But the success came in 1944, after a year of relatively futile effort.98
In summary, the interdiction program in central Burma had not succeeded by the end of 1943. Goods and equipment still moved into northern Burma, although on a reduced scale; the Burma railroad system was still usable. On the other hand, the campaign was not a
complete failure. Some irreplaceable locomotives and rolling stock had been destroyed, warehouses full of goods burned, railway yards damaged, and certain key bridges closed for varying periods. But the real measure of success achieved was scarcely discernible to the flyers. Upset train schedules, delays caused by damage to bridges and trackage, loss of supplies, and necessity of employing so much equipment and so many laborers in repair work affected the enemy war effort. Repaired bridges could no longer bear normal loads, and rebuilt locomotives were not up to standard. Possibly, if considered as a campaign of attrition, it could be called successful, for the enemy had at least begun to feel the effects of the regular bombings. But as a preparation for an all-out ground attack to reconquer Burma, it was a failure.99
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