The U.S. Army Campaigns
A bullett-scarred monolith serves as a cover for U.S. infantrymen. (National Archives)
World War II was the largest and most violent armed conflict in the history of mankind. However, the half century that now separates us from that conflict has exacted its toll on our collective knowledge. While World War II continues to absorb the interest of military scholars and historians, as well as its veterans, a generation of Americans has grown to maturity largely unaware of the political, social, and military implications of a war that, more than any other, united us as a people with a common purpose.
Highly relevant today, World War II has much to teach us, not only about the profession of arms, but also about military preparedness, global strategy, and combined operations in the coalition war against fascism. During the next several years, the U.S. Army will participate in the nation's 50th anniversary commemoration of World War II. The commemoration will include the publication of various materials to help educate Americans about that war. The works produced will provide great opportunities to learn about and renew pride in an Army that fought so magnificently in what has been called "the mighty endeavor."
World War II was waged on land, on sea, and in the air over several diverse theaters of operation for approximately six years. The following essay is one of a series of campaign studies highlighting those struggles that, with their accompanying suggestions for further reading, are designed to introduce you to one of the Army's significant military feats from that war.
This brochure was prepared in the U.S. Army Center of Military History by Arnold G. Fisch, Jr. I hope this absorbing account of that period will enhance your appreciation of American achievements during World War II.
GORDON R. SULLIVAN
General, United States Army
Chief of Staff
In late September 1944 the Joint Chiefs of Staff (JCS) in Washington decided to invade Okinawa, the largest island in the Ryukyu Islands, as part of a strategy to defeat Japan. The effort was code-named Operation ICEBERG. Okinawa had initially emerged as an objective in the spring of 1943, when the Allies believed that an invasion of the home islands might be necessary to force Tokyo's surrender. Possession of Okinawa would give the American forces additional, better-positioned air bases for intensifying the air campaign against the home islands and also provide important anchorages and staging areas for the huge, ambitious effort needed to invade Japan.
26 March--2 July 1945
Beginning in late September 1944 American aircraft and submarines began to tighten a noose around the Ryukyus, making surface shipping extremely hazardous for the Japanese. Heavy bombers of the Fourteenth and Twentieth Air Forces and carrier planes from Admiral William F. Halsey's Third Fleet struck repeatedly at Japanese positions in the Philippines, Taiwan, and the Ryukyu Islands. On 29 September B-29 bombers conducted the initial reconnaissance mission over Okinawa and its outlying islands. On 10 October nearly two hundred of Admiral Halsey's planes struck Naha, Okinawa's capital and principal city, in five separate waves. The city was almost totally devastated. The American war against Japan was coming inexorably closer to the Japanese homeland.
Neither the outbreak of hostilities in China during the 1930s nor the ensuing war in the Pacific initially had much impact on the inhabitants of the Ryukyu Islands, a chain running southwest from the Japanese home island of Kyushu toward Taiwan. Despite its size, of approximately 480 square miles and its population of perhaps 500,000, Okinawa had neither surplus food nor a great deal of industry to assist the Japanese effort. Its harbor facilities were unsuitable for large warships. The island's main contribution to the war effort lay in the production of sugarcane, which could be converted into commercial alcohol for torpedoes and engines.
Okinawa is sixty miles long and from two to sixteen miles wide. Its topography and irregular terrain facilitated the defensive. The northern
The Pacific and Adjacent Theaters
part of the island is rugged and mountainous, with considerable tree cover; agriculture is restricted to small terraces and coastal areas. The central portion consists of a 50,000-acre hilly, dissected limestone plateau. The land rises gently from this central plain to a broken 30,000-acre plateau in the south. This plateau is bounded by steep escarpments descending to raised beaches, except at the extreme southern tip, where the escarpment becomes a sea cliff. The island is dotted overall with hills, ravines, and caves--the last of natural rock and coral, providing any defender with ready-made fortifications and storehouses.
In early 1944, as American forces began to approach the home islands of Japan from the south and southwest, the peaceful status of the Ryukyus began to change. On 1 April Lt. Gen. Masao Watanabe activated the 32d Army for duty on Okinawa, with its headquarters in the suburbs of Naha. Over the next twelve months the 32d Army received a steady stream of reinforcements and devoted itself to construction of elaborate fortifications, including countless concrete pillboxes and fortified positions, tank traps, and minefields. After the Americans breached the Marianas defense line in July, some 1,500 miles to the southeast, these defensive preparations accelerated. Lt. Gen. Mitsuru Ushijima replaced General Watanabe as commanding general, and his headquarters staff began digging in at Shuri, Okinawa's second largest urban area, cultural center, and ancient royal capital.
Less than two miles inland from Naha on the western coast, Shuri is situated on high ground, surrounded by the most rugged terrain in the southern third of the island. Lower than the mountains in the north, the hills around Shuri still provide excellent vantage points to the north and south and across the coastal regions; moreover, their varied texture, with meandering escarpments, steep slopes, and abrupt ravines, make them ideal for defensive operations. General Ushijima consolidated the bulk of his forces in what the Japanese termed the Shuri defensive area, where they improved on the natural defenses by constructing a network of pillboxes, tunnels, caves, and fortified burial tombs. Here, along what would become the "Shuri Line" to the American forces, the Japanese 32d Army would make its stand, meeting the enemy on its own terms in a series of concentric positions where minor infantry actions and antitank ambushes would be most successful and American shipboard fire support least effective.
Reinforcements for the 32d Army continued to arrive on Okinawa from the Japanese home islands throughout the summer and autumn of 1944. As the months went by, however, the lack of available shipping and the growing pressure from American air and sea units made this
augmentation increasingly difficult, if all the more urgent, after the American assault on Iwo Jima in February 1945.
Nevertheless, by late March 1945, General Mitsuru Ushijima had organized a formidable defense structure. His major ground units were the 24th Division, a triangular heavy division with organic artillery and three infantry regiments, each with three battalions; the 62d Division, a pentagonal light division with two brigades, each with five infantry battalions (five rifle companies per battalion), but with no artillery; the 44th Independent Mixed Brigade; and the 27th Tank Regiment. Additional forces such as naval personnel, engineers, communications troops, and other miscellaneous units brought the estimated strength of the 32d Army to over 77,000 Imperial troops. To these figures must be added about 20,000 Okinawa Home Guards (Boeitai), and even 750 male Okinawan middle-school students who were organized into "Blood and Iron for the Emperor" (Tekketsu) volunteer units and trained for combat, as well as thousands of other Okinawans conscripted as civilians for labor and other service duties. Since no accurate records existed for many of the Okinawans drafted into the 32d Army, the exact strength of Japanese units at the time of the American invasion cannot be stated precisely, but it certainly exceeded 100,000 men.
While the staff of the Imperial Japanese Headquarters grimly prepared for the likely invasion, the American Pacific commanders continued to plan and stage for their role in the onslaught. The JCS decision meant that the command relationship, tactics, and logistics associated with "island hopping" had to be modified and expanded. Admiral Chester W. Nimitz's Central Pacific amphibious assaults had required relatively few ground troops, but an invasion of the Ryukyus--so close to the Japanese home islands would require an entire field army.
As Commander, Pacific Ocean Areas, Nimitz provided strategic direction while a vast Army-Navy force, designated Central Pacific Task Forces, assembled under Admiral Raymond A. Spruance, the Fifth Fleet commander. Vice Adm. Richmond K. Turner headed the Joint expeditionary force, Task Force 51, which was assigned the actual seizure of Okinawa and a number of other islands in the Ryukyus chain. Task Force 51 was an Army, Navy, and Marine Corps organization that included the ground expeditionary force itself, Task Force 56, as well as its transport and supporting air and sea units.
Lt. Gen. Simon B. Buckner, Jr., U.S. Army, commanded the assault troops of Task Force 56 as commander of the Tenth Army. The Tenth Army's principal components were the U.S. Army XXIV Corps, under Maj. Gen. John R. Hodge and consisting of the 7th and 96th Infantry Divisions, both reinforced, and the U.S. Marine Corps III
Island of Okinawa
Amphibious Corps, commanded by Maj. Gen. Roy S. Geiger and consisting of two reinforced Marine divisions, the 1st and the 6th. Other major elements were Tenth Army's Tactical Air Force, commanded by Maj. Gen. F. P. Mulcahy, USMC; the Army's 77th Infantry Division under Maj. Gen. Andrew D. Bruce, reinforced for an assault on the western islands of the Kerama Retto and Keise Shima; and two additional divisions in floating reserve: the U.S. Army 27th Infantry Division under Maj. Gen. George W. Griner, Jr., and the U.S. Marine Corps 2d Division under Maj. Gen. Thomas E. Watson. In all, the Tenth Army marshaled approximately 183,000 troops for the various assault phases. Almost 116,000 men in five divisions, all reinforced with tank and tractor battalions and attached service units, were to make the initial landings.
The first American troops to set foot in the Ryukyus were members of the 3d Battalion Landing Team, 305th Regiment, 77th Division, who landed in the Kerama Islands, fifteen miles from Okinawa at 0804 on 26 March 1945. Three other subsidiary landings followed immediately, and by 31 March American forces had secured all the islands of the Kerama group and mopping-up operations were under way. In these preliminary operations, the 77th Division suffered 31 dead and 81 wounded, while Japanese dead and captured numbered over 650. On 3 1 March the Americans landed without opposition on Keise Shima, four islets just eight miles west of the Okinawan capital of Naha. General Buckner immediately positioned two artillery battalions on Keise Shima, with twenty-four 155-mm. guns of the 420th Field Artillery Group to support the attack on Okinawa itself.
Tenth Army Invasion Plan
1 April 1945
While operations in the Kerama Islands an-d Keise proceeded, other American forces were busy sweeping the extensive Japanese minefields and conducting underwater demolition work on the obstacles in front of the proposed Okinawa landing beaches. The approaches were
cleared on 29 and 30 March, despite sporadic Japanese air attacks on the minesweeping and demolition forces. Meanwhile, suspected Japanese positions on the island continued to receive heavy and sustained bombardment from the air and sea.
The main landing on Okinawa (L-Day) had been set for 1 April 1945, Easter Sunday. The day began and ended with the heaviest concentration of naval gunfire ever expended to support an amphibious landing. Gathered off the invasion beaches were 10 older American battleships, including several Pearl Harbor survivors--the USS Tennessee, Maryland, and West Virginia--as well as 9 cruisers, 23 destroyers and destroyer escorts, and 117 rocket gunboats. Together they fired 3,800 tons of shells at Okinawa during the first 24 hours. Okinawans had long been resigned to the severe typhoons that sweep their land, but nothing in their experience prepared them for the tetsu no bow--the "storm of steel"--as one Okinawan characterized the Americans' April assault on the island.
Meanwhile, in a feint designed to distract the enemy from the actual landing sites--the Hagushi beaches on the western side of the island--the 2d Marine Division conducted a demonstration off the Minatoga beaches on the southeastern coast. The Marine assault waves simulated an actual amphibious landing in every respect, turning back only at the last minute. The ruse was repeated on L plus 1, and captured documents later revealed that the Japanese had been convinced that they had repelled a major American landing.
At 0830 the 7th and 96th Infantry Divisions of the XXIV Corps and the 1st and 6th Marine Divisions of the III Amphibious Corps crossed the Hagushi beaches, with 16,000 troops landing unopposed in the first hour. By nightfall more than 60,000 were ashore. From their positions on the high ground around Shuri Castle, the Japanese observed the amphibious assault but, apart from isolated artillery rounds and some sniping, made no effort to engage the invaders.
The lack of opposition puzzled the Americans. One GI from the 7th Division, standing on a hill south of the Bishi River soon after the landing, expressed what might well have been a common thought: "I've already lived longer than I thought I would." But the absence of fighting on the beaches reflected a deliberate Japanese defensive strategy. Although as late as mid-July 1944 the 32d Army had planned to fight the Americans on the landing beaches, once Japanese leaders digested their experiences on Saipan, they altered their defensive concepts dramatically. Rather than mass their ground forces on the shoreline, they now planned to focus their defensive strength in the interior, concentrated around strongpoints in the central and southern parts of the
The invasion begins on the Hagushi beaches. (National Archives)
island. Similarly, Japanese naval and air elements would be committed only after the main landing; then they would attack the American fleet and resupply vessels offshore, isolating the invasion force.
Without any major opposition at the beaches, elements of the 7th Infantry Division thus crossed from the west to the east coast of Okinawa quickly on the afternoon of 2 April. Elements of the 1st Marine Division reached the eastern shore the following day. The movement severed the smaller Japanese force north of the invasion beaches from the defender's main body in the south. Meanwhile, beginning on 6 April fierce but uncoordinated kamikaze and conventional air attacks began to strike the American fleet. On 6-7 April the Japanese also attempted a surface raid from Kyushu, led by the super battleship Yamato, but the ships were detected almost immediately by an American submarine, and aircraft from the fast carriers of Task Force 58 sank the Japanese ships with relative ease.
On the American left wing, the 6th Marine Division immediately began the conquest of northern Okinawa, driving up the Ishikawa Isthmus on 4-7 April with three regiments abreast. The land was mountainous and wooded, with the Japanese defenses concentrated on a twisted mass of rocky ridges and ravines on the Motobu Peninsula called Yae-Take. Not until 18 April were the marines able to clear the
major Japanese fortifications there, later noting that, "practically every type of maneuver was employed and all types of supply problems encountered." Mop-up operations against enemy guerrillas occupied both divisions of the III Amphibious Corps until May, when they finally were able to turn their attention southward.
While the marines cleared the northern portion of Okinawa, four Army regiments of the XXIV Corps wheeled south across the narrow waist of Okinawa. By 4 April Hodge had deployed, west to east, the 383d and 382d Infantry of the 96th Division and the 184th and 32d Infantry of the 7th Division. When the troops moved out the following day, they encountered the first sustained, fierce enemy resistance along; the well-fortified high ground to the south. The next few days found the 1st and 3d Battalions, 383d Infantry, engaged in desperate hand-to-hand fighting in west-central Okinawa along Cactus Ridge, about five miles northwest of Shuri, while the 184th Infantry assaulted a hill to the east known as the Pinnacle, defended by three platoons of the 14th Independent Infantry Battalion. By the night of 8 April the XXIV Corps had finally cleared these and several other strongly fortified outposts guarding the Shuri Line. But they had suffered over 1,500 battle casualties in the process, while killing or capturing about 4,500 Japanese--and the battle had only just begun.
During these initial engagements the Japanese demonstrated their awareness of the value of indirect fire support. A captured map detailed a well-conceived plan for using artillery and mortars, prepared in part by the recognized Japanese artillerist, Lt. Gen. Wada Kojo. Because of the great dispersion of their pieces and the inadequacy of their communication, however, they often were incapable of massing fire from more than one battery. Moreover, they showed little awareness of the value of persistent harassing or interdictory fires deep within enemy lines. Nevertheless, the disposition itself, together with carefully camouflaged and protected positions, made it extremely difficult to silence the Japanese mortars and field pieces.
The next American objective was Kakazu Ridge, consisting of two hills with a connecting saddle, a part of Shuri's outer defenses. The Japanese had prepared their positions well and fought tenaciously. As the 96th Division's assault against the ridge stalled on 9-10 April, General Ushijima and his staff debated the merits of taking the offensive. The 32d Army chief of staff, Lt. Gen. Isamu Cho, favored such a move, while only the senior operations officer, Col. Hiromichi Yahara, strongly dissented. Ushijima ultimately agreed with Cho, and thus on the evening of 12 April three battalions of the 62d Division and three of the 24th assembled opposite the American positions across the
U.S. and Japanese Lines
12 April 1945
entire front. Only at the last minute did Colonel Yahara succeed in having the attacking force reduced to four battalions.
The Japanese attack on the 96th Division was heavy, sustained, and well organized. Following a five-hour artillery and mortar barrage, the enemy began infiltrating the American lines near the Kakazu
Ridge around midnight of 12-13 April. Japanese timing was good; American casualties had been heavy and reinforcements, although available, had not yet been brought into the line. After fierce, close fighting the attackers retreated, only to repeat their offensive the following night. A final assault came around 0300 of 14 April and was
again repulsed. The entire effort led 32d Army's staff to conclude that the Americans were vulnerable to night infiltration, but that their superior firepower made any offensive Japanese troop concentrations extremely dangerous. Commanders, therefore, were ordered to return to their previous defensive positions.
While the XXIV Corps prepared to resume its offensive against the Shuri defenses, the Marine conquest of the Motobu Peninsula facilitated the 77th Division's assault on Ie Shima, a small island three and one-half miles off the western end of the peninsula. The division's 305th and 306th Infantry landed on 16 April, followed almost immediately by the 307th, which had been held in reserve, when resistance by elements of the 2d Infantry Unit proved determined. The heaviest fighting was at Bloody Ridge, south of Iegusugu Mountain (which the GIs also named "the Pinnacle"--one of several so-called pinnacles featured in the Ryukyus Campaign), and on Iegusugu itself.
Near Bloody Ridge the men of the 77th faced a wide variety of hazards, from heavy mortar barrages, to individual suicide charges by explosive-laden sappers intent on blowing up as many Americans as possible, and even to Japanese women armed with spears. During the fighting on Ie Shima the well-known war correspondent Ernie Pyle was killed and later buried in the 77th Division cemetery there. The island was declared secured on 21 April and became an ideal base for air operations against neighboring Okinawa.
Meanwhile, General Hodge marshaled his entire XXIV Corps opposite the main Japanese positions at Shuri. Hodge hoped to break through and seize the highway extending across the island between the towns of Naha on the west coast and Yonabaru on the east. The 27th Division, which had landed on 9 April from floating reserve, relieved part of the 96th and reinforced the remainder. The three divisions would attack abreast, with the 27th on the right along the west coast of Okinawa, the 96th in the middle, and the 7th on the east. The average front of each division was only about a mile and half. The mission of the 27th Division was to seize Kakazu Ridge, the western portion of the Urasoe-Mura Escarpment that lay about a half mile beyond, and the hilly country and coastal plain still farther south, through which ran the Naha-Yonabaru highway. From the center, the 96th was to capture Shuri itself and the area beyond to the highway, while in the east the 7th Division was to capture the high ground in its sector, Hill 178, and push on to the highway nearest Yonabaru. But the corps' immediate objectives, west to east, were Kakazu Ridge, Nishibaru Ridge, and the Tanabaru Escarpment, which together constituted the outer defenses of the Shuri Line.
A massive barrage by 27 battalions of corps and division artillery--the largest concentration (324 pieces) employed during the Pacific war--opened the assault on the morning of 19 April. Six battleships, 6 cruisers, and 6 destroyers added their weight to the bombardment, which was followed by the largest single air strike of the Okinawa campaign--650 Navy and Marine planes attacking the enemy positions with napalm, rockets, bombs, and machine guns. The effect was negligible. The Japanese, deep within their cave defenses, were only marginally affected. The attackers found the formidable Japanese defenses almost completely intact. An armor assault on Kakazu Ridge, launched without sufficient infantry support in the hope of a rapid breakthrough, failed with the loss of twenty-two tanks. Elsewhere along the front the results were similar.
Despite the tremendous effort of 19 April at places given such exotic names as Skyline Ridge and Tombstone Ridge, the Japanese defenses held. The day was marked by considerable hand-to-hand combat and heavy casualties on both sides. Surveys after the battle revealed that the Japanese, as they so often did on Okinawa, dug many of their positions into the reverse slopes of the ridgelines, away from the anticipated direction of attack. Because of the odd angle of the reverse slope, they were much less vulnerable to artillery fire or direct assault. Japanese defenders could wait out an artillery barrage or aerial attack in relative safety, emerging from the caves to rain mortar rounds and grenades upon the Americans advancing up the forward slope. Although flamethrower tanks demonstrated their value in clearing several cave defenses, there was no breakthrough, and the XXIV Corps lost 720 dead, wounded' and missing. The losses might have been greater, except for the fact that the Japanese had practically all of their infantry reserves tied up farther south, held there by an American landing feint off the Minatoga beaches that coincided with the 19 April attack.
The weary attackers resumed the offensive the following morning, now aware that breaking through the outer Shuri defenses would be slow and costly. Along the western coast, two battalions of the 165th Infantry moved to the 27th Division right flank, bypassing the main Shuri defenses and approaching Machinato airfield and Naha, three miles beyond. Both were important objectives. But further movement south was blocked for a full week, until 27 April, by a strong Japanese defensive position called "Item Pocket."
While Item Pocket was being reduced, other elements of the American 27th Division, along with the 7th and 96th Divisions, continued to batter the outer defenses of Shuri. The engagements continued
The hills of Okinawa, honeycombed with well-manned caves and dugouts. (National Archives)
to be intense, with the American forces overcoming Japanese cave defenses with flamethrower tanks and small demolition crews, using what General Buckner termed "blowtorch and corkscrew" methods. Clearly the enemy was trying to make the invaders pay dearly for every foot of ground. But the Americans sometimes managed to take the defenders by surprise, as on 23 April when two companies of the 1st Battalion, 105th Infantry, 27th Division, advanced up the Urasoe-Mura Escarpment and found themselves in the midst of milling Japanese troops. A wild melee ensued in which bayonets, clubs, and grenades were used freely, and more than one hundred defenders were killed in about an hour. S. Sgt. Nathan S. Johnson led the assault and at one particular moment, jumped over a mound of earth to find himself face to face with a dozen startled Japanese. Johnson later was credited with having killed more than thirty enemy.
Because of repeated individual efforts on the part of men such as Sergeant Johnson, the first defensive positions around Shuri fell on 24 April, with the exception of the Item Pocket area. A heavy mist and fog on the night of 23-24 April enabled the remaining defenders to slip away to defensive positions farther south, and the following day the 7th Division walked up Hill 178 in the east, the 96th occupied the Tanabaru
Escarpment and Nishibaru Ridge in the center, and the 27th Division took up positions along the Urasoe-Mura Escarpment.
During preparations for an assault on the defenses closer to Shuri, there was a general regrouping of the weary American forces. Both the 27th and 96th Divisions had suffered heavy casualties and needed a rest to assimilate replacements, so the former was relieved by the 1st Marine Division from the north and the latter by the 77th, now brought to Okinawa and relatively fresh, despite its engagements in the Keramas and on Ie Shima. These changes were complete by 30 April. While the 96th regrouped, the 7th Division remained on line for about two weeks, then was relieved by the 96th.
During its last days on line, the 7th Division was repeatedly frustrated in its efforts to capture the Kochi Ridge, about a mile northeast of Shuri itself. The failure was caused primarily by sketchy intelligence concerning the mutually supporting Japanese positions, including artillery, that hindered any divisional-size attack. Here, as elsewhere on Okinawa, the thorough integration of the Japanese defenses over the entire front permitted concentrated firepower to be brought to bear on the American attackers.
To the west, the 96th Division had an equally tough time. Its objective was the eastern end of the Urasoe-Mura Escarpment, known as the Maeda Escarpment after the village of Maeda just over the south slope. Again, the Japanese had prepared their positions in classic reverse slope fashion and, in fierce fighting, successfully withstood the 96th's attack of 26-29 April.
On 29 April the 307th Infantry, 77th Division, replaced the 381st Infantry, 96th Division, on part of the Maeda Escarpment, and on the following day General Bruce's 77th took over the 96th Division's entire zone of action. By that time the 381st Infantry had suffered 1,021 casualties, 536 of them at Maeda in four days, and was down to 40 percent of its authorized personnel. Nevertheless, the battle for the escarpment continued, ending only on 7 May and resulting in equally heavy casualties for the 77th Division. But it also cost the Japanese over 3,000 dead, and its loss ultimately unhinged all of their defenses around Shuri.
Amid the battle for the Maeda Escarpment the staff of the 32d Army held another war council one hundred feet below Shuri castle. Many of the officers were tired of defensive fighting and saw no prospect of success in a battle of attrition. Once again the debate centered around the strong personalities of General Cho and Colonel Yahara, and once again Cho, and those favoring offensive action, prevailed. On 4 May the 32d Army thus launched another general offensive. The 24th Division spearheaded the main ground attack
Through Outer Shuri Defenses
19-24 April 1945
with both tanks and infantry against the center and eastern portion of the XXIV Corps front, held by the 7th and 77th Divisions. In support, elements of the 26th Shipping Engineer Regiment, armed with satchel charges and light arms, made an attempt at an amphibious assault on the west coast behind American lines, while the 23d
Engineers did the same on the east. The offensive also coincided with kamikaze aircraft and boat attacks against American supply lines and shipping.
The offensive marked the first time in the campaign that the Japanese used artillery batteries in the open. By doing so the enemy
was able to deliver more than 13,000 artillery rounds in support of the attack. However, the Japanese paid a steep price. Attempts to conceal the artillery positions with smoke pots and to keep American observation aircraft at a distance with antiaircraft guns failed. The smoke dissipated too quickly, and American area artillery barrages drove the antiaircraft crews to cover, enabling observation planes to pinpoint the enemy artillery. American counterbattery fire destroyed nineteen field pieces on 4 May and forty more over the next two days.
Overly ambitious and poorly executed, the Japanese attack was a failure. Although the Japanese used both daylight attacks and night infiltrations, some penetrating over 1,000 yards to the Tanabaru Escarpment, all were blunted. The amphibious operations were a complete fiasco, as were the suicide boats. Only the kamikaze planes were moderately successful, sinking or damaging 17 ships and inflicting 682 naval casualties. The 32d Army lost approximately 5,000 troops, including all of its final reserves. Moreover, General Ushijima understood that the failed offensive was a turning point. If sustained offensive action was not possible, defeat was inevitable, and all the 32d Army could hope to do was its duty--by inflicting maximum casualties on the invaders.
After consolidating the American positions along the line, General Buckner was anxious to resume the offensive. He ordered a coordinated Tenth Army attack on the Shuri defenses for 11 May, two corps abreast: the III Amphibious Corps on the west with the 6th and 1st Marine Divisions, the XXIV Corps on the east with the 77th and 96th Infantry Divisions, and the 7th Division in corps reserve. General Buckner planned an envelopment of Shuri, with most of the Marine forces pushing south along the western coastline, the Army divisions doing the same in the east, and a strong holding force exerting pressure in the center.
The attack was launched on 11 May as scheduled, but despite coordinated action along the entire front, the assault soon deteriorated into a series of intense fights for specific points in each of the three sectors. During ten days of constant fighting, from a rise known as "Sugar Loaf" near the western coast and less than 500 yards northeast of Naha to Conical Hill overlooking the eastern coastal plain outside Yonabaru, the Japanese defenders held, forced only into several small, localized retreats. Marine veterans of the 6th Marine Division remember 16 May at Sugar Loaf as the bitterest day of fighting on Okinawa. The fighting was also intense throughout the front during May, with the 1st Marine Division battling across Dakeshi and Wana Ridges; 77th Division infantrymen heavily engaged at places with names like
"Chocolate Drop," the "Wart," and "Flattop"; and the 96th Division struggling up Dick, Oboe, and Conical Hills.
The first crack in the Shuri inner defenses came on 13 May in the extreme east, along Nakagusuku Bay, later renamed Buckner Bay by the American forces. There the 383d Infantry, 96th Division, and the 763d Tank Battalion struggled up Conical Hill. Rising 476 feet above the Yonabaru coastal plain, this feature was the eastern anchor of the main Japanese defenses and was defended by about 1,000 Japanese, heavily armed with 75-mm. artillery and mortars. The seizure of its eastern slopes gave General Buckner hope that the 7th Division could slip through the corridor by Buckner Bay and quickly envelop the enemy, but that was not to be. From 22-29 May progress slowed as the so-called plum rains turned Okinawa into a mass of mud. To make matters worse, during this period the Japanese launched a series of damaging air raids on Okinawa from Kyushu and Taiwan that complicated American resupply efforts.
In the west, the 6th Marine Division crossed the rain-swollen Asato River on 23-24 May and entered Naha. The Okinawan capital was largely deserted, although the Americans encountered resistance in the eastern section. The city itself had no tactical value to the invaders, except for offering a western route to the next objective south and eastward. The Kokuba Hills extend east from Naha, guarding the south and southwest approaches to Shuri. As the Americans pressed eastward into the hills, Buckner hoped to envelop Shuri and trap the main Japanese defending force.
Fierce resistance was gradually overcome toward the end of May as the Americans pressed Shuri itself from three sides. Pfc. Clarence B. Craft, a rifleman with Company G, 382d Infantry, 96th Division, was a new replacement seeing his first action. Moving up the slope of Hen Hill, just northeast of Shuri, he was one of six soldiers stopped by enemy fire from the reverse slope. That fire wounded three men and drove two more to cover. Craft kept on toward the crest, throwing grenades and finally firing point-blank into the enemy defenders. He destroyed one machine gun nest and threw a satchel charge into a cave after chasing a number of Japanese soldiers to cover in the rock opening. In all, Private Craft was cited for more than twenty-five enemy casualties that day, earning a Medal of Honor for his heroic action.
Meanwhile, on 21 May, the same day the 96th Division captured the eastern side of Conical Hill, General Ushijima had called all 32d Army division and brigade commanders together for a night conference in the caves below Shuri. The island's defenders realized that they
"Messing in the Open on Okinawa," by John A. Ruge. (Army Art Collection)
had inflicted severe casualties on the Americans--some twenty-six thousand between the two attacking corps, the heaviest of the Pacific war--but the Japanese had suffered even more devastating losses, some sixty-four thousand killed in the fighting around Shuri alone. Their three main combat units, the 62d Division, the 24th Division, and the 44th Independent Mixed Brigade, were wasting away. As second-rate troops and labor forces replaced fallen veteran combat soldiers, the capabilities of these units were reduced.
The issue before the Japanese commanders was a simple one: should the 32d Army make its stand at Shuri, which would ultimately be overwhelmed, or attempt a retreat to secondary defensive positions in the south? There were arguments to be made on both sides. Certainly the best prepared defenses were at Shuri, as well as the largest supply of stores. The Japanese were well dug in, whereas the Americans were fighting from shallow foxholes, in defilade, or simply exposed. On the other hand, if the 32d Army could escape to the south its forces had a chance to prolong the struggle and thereby inflict even more casualties on the invaders. Determined to cause as
much harm as possible to the American invaders, the Japanese officers decided to attempt a tactical redeployment farther south.
The withdrawal of supplies and the wounded began the following night and went largely unnoticed. From 23 May until the end of the month the overcast weather limited aerial observation over the Japanese rear areas. Although some flights were made between 23-25 May, with pilots reporting several groups of Japanese moving south, the Americans thought they were civilians. Since the 32d Army had fought so hard for so long in front of Shuri, American staff officers stubbornly believed the enemy would fight there to the bitter end.
On 26 May, with the exodus accelerating, aerial observers reported thousands of "civilians" along with trucks and some tanks headed south. Pilots strafed the columns and reported some of the Japanese exploded when hit by tracers, evidence that they likely were carrying satchel charges. Even though naval gunfire soon engaged the retreating Japanese, the Americans continued to believe that the bulk of the Japanese defenders would remain in place. As late as 28 May the Tenth Army intelligence officer noted in a staff meeting that it "now looks as though the Japanese thinks holding the line around north of Shuri is his best bet."
The Americans were soon to learn otherwise. On 29 May units of the 1st Marine Division entered Shuri castle, and the 77th Division entered the devastated town on 31 May. By then only a few Japanese remained in the tunnels below the castle heights, and the fall of Shuri did not conclude the fighting on Okinawa. Instead, the successful Japanese redeployment necessitated more than three weeks of pursuit and combat by the Americans to end organized resistance. Although the continuation of the fight in the extreme south failed to delay the planned American development of airfields and harbors--this began long before the fighting ended--it did result in additional American casualties, just as General Ushijima intended.
Nearly ten inches of rain fell on Okinawa during the last ten days in May, slowing American progress and giving the remainder of the Japanese 32d Army a chance to escape. Each retreating defender carried with him no more than a twenty-day ration and as much equipment and supplies as he could carry. The new Japanese defensive line now lay roughly east to west athwart the Yaeju-Dake Escarpment, the largest coral outcropping on the Okinawa battlefield. There, in the southeast corner of the island, the Japanese defenders burrowed in for a final stand.
Meanwhile, General Buckner shifted the Marine-Army corps boundary to the west as of noon on 4 June, so that the entire Yaeju-
Dake Escarpment fell within the zone of the XXIV Corps. In the west, units of the 6th Marine Division bypassed Japanese resistance with an amphibious assault on the north coast of the Oroku Peninsula, immediately south of Naha. The landing went well, but the subsequent battle for the peninsula lasted another ten days.
On 10 June, as men of the 381st and 383d Infantry, 96th Division, attacked the high peaks of the Yaeju-Dake Escarpment, General Buckner personally urged General Ushijima in writing to surrender. Although Ushijima did not receive the note until 17 June, it mattered little, since the testimony of survivors made it clear that the commander of the 32d Army had no intention of capitulating. On 12 June Col. Francis Pachler directed the 1st and 3d Battalions, 17th Infantry, 7th Division, in a night assault on their portion of the Yaeju-Dake, and soon the entire defensive line was under attack. The battle for the escarpment lasted five days, during which napalm and gasoline hoses played a major role in dislodging the enemy from the caves and coral outcroppings. Apart from a pocket of resistance near the village of Medeera, south of Yaeju-Dake, a cohesive Japanese defensive effort disappeared by the evening of 21 June.
Between the fall of Shuri and the collapse of the enemy front at Yaeju-Dake, Tenth Army lost another 1,555 killed and 6,602 wounded. Among the dead were the Tenth Army commander, General Buckner, killed in action on 18 June, and Brig. Gen. Claudius M. Easley, assistant commander of the 96th Division, killed the following day. General Geiger, senior commander on Okinawa, assumed command of the Tenth Army and ably directed the campaign to its conclusion.
Among the Japanese, the incidence of suicide soared during the final days. An examination of enemy dead revealed that, rather than surrender, many had held grenades against their stomachs, ending their personal war in that manner. Men of the 184th Infantry encountered one Japanese soldier who approached a field artillery outpost, sprang into full view, and announced in understandable English: "Watch out! I'm going to blow my head off!"--and then did just that.
General Ushijima and his chief of staff, Lt. Gen. Isamu Cho, committed ritual suicide, seppuku, on 22 June at Hill 89 near the town of Mabuni on the southeast coast. Scattered resistance continued, however, for another week. Between 23 and 30 June, Tenth Army units sustained another 783 casualties in mopping-up operations. During that same period 8,975 more Japanese soldiers were killed and 2,902 were captured. Finally, on 2 July America's bloodiest campaign against Imperial Japan formally ended.
The capture of the Ryukyu Islands erased any hope Japanese military leaders might have held that an invasion of the home islands could be averted. Long before the firing stopped on Okinawa, engineers and construction battalions, following close on the heels of the combat forces, were transforming the island into a major base for the projected invasion of the Japanese home islands. A soldier walking back over the terrain for which he had fought so hard just weeks before might not have recognized the landscape, as hills were leveled' ravines filled' and water courses altered to make way for airstrips, highways, and ammunition dumps. The first American-built airfield on Okinawa, a 7,000-foot airstrip at Yontan, just east of the invasion beaches, was operational by 17 June. By the end of the month a total of five air bases were ready for the heavy bombers that could soften up the islands of Kyushu and Honshu for the invasion that everyone believed inevitable. Operationally, the campaign for the Ryukyus had succeeded in its mission.
In terms of tactical lessons learned' the picture is somewhat different. The force of American arms prevailed on the ground certainly, but the battle for Okinawa had seen no breakthrough tactical or technical innovations. The adjustments that appeared, such as greater cooperation between armor and infantry, were adaptations or improvements born from American experiences fighting the Japanese in a number of earlier Pacific campaigns. Basically, the struggle pitted American firepower against Japanese fortifications, with the victory won by the actions of individual foot soldiers and their small unit leaders.
Logistics, always a crucial and often a problematic aspect of any modern invasion, presented the experienced Tenth Army planners with the usual difficulties, but offered no new lessons for future logisticians. During late April the commander of the 77th Division, General Bruce, urged that his division make an amphibious landing at Minatoga, behind the main Japanese defenses near Shuri, as the 77th had done at Leyte, but General Buckner rejected the idea, judging the Minatoga beaches unsuitable for supplying a division-size force once ashore.
Unloading of initial assault shipping across the Hagushi beaches was more than 80 percent completed by 16 April, ahead of schedule. Despite a critical shortage of 155-mm. ammunition, the discharge of supplies kept pace until 6 May. Unloading then began to lag, falling 200,000 tons behind by 15 June. The chief problem was the failure to capture the port of Naha, with its harbor and dock facilities, as early as had been planned. Nevertheless, despite the need to continue supplying the offensive across
the invasion beaches and elsewhere along the coastline, supplies continued to be unloaded at an average of 22,200 tons per day.
Once the materiel was ashore, there were no particular difficulties moving supplies forward to the front lines until late May, when two solid weeks of rain turned the island into a quagmire. The only recourse then was to bring supplies ashore to forward dumps by a variety of landing craft and by amphibious trucks (DUKWs or "ducks"), the supply procedure used extensively in New Guinea. The more isolated forward units sometimes were supplied by plane, often using Navy torpedo bombers, capable of more accurate, albeit considerably smaller, air drops than the C-47.
Although the initial American assault units carried with them a thirty-day supply of rations, ammunition, and equipment, the battle for the Ryukyu Islands lasted considerably longer and was fiercely fought. The price was dear for both sides. American casualties were the highest for any campaign in the Pacific--49,151, including 12,520 killed or missing, and 36,361 wounded. The Army alone suffered 4,482 killed 93 missing, and 19,099 wounded in addition to another 15,613 non-battle casualties. Marine Corps and Navy losses were also high. The American fleet lost 36 ships sunk, with another 368 damaged. Taken together, the services lost 763 airplanes. Japanese losses were even more staggering: approximately 110,000 combatants and service troops killed and another 7,400 captured. Since many Okinawan residents fled to caves where they subsequently were entombed the precise number of civilian casualties will probably never be known, but the lowest estimate is 42,000 killed. In all likelihood, somewhere between one-tenth and one-fourth of the civil population perished.
The fighting had been devastating, but it might have been worse had it not been for the work of the Tenth Army's psychological warfare units before and during the invasion. Between 25 March and 17 April carrier planes from the supporting Fifth Fleet dropped some five million leaflets on the islands, as well as copies of the psychological warfare office's newspaper, the Ryukyu Shuho, which attracted considerable attention among enemy soldiers and civilians alike. Other propaganda tools--such as tank-mounted amplifiers, aircraft with loudspeakers, and remotely controlled radios parachuted behind enemy lines--contributed to the psychological operations effort by underlining the harsh conditions the defenders were enduring, disparaging Japanese chances for success, and promising humane treatment for those who offered no resistance to the approaching Americans. Regardless of the machinery used the objective was the same: to depress Japanese morale so that enemy soldiers would surrender rather than resist, and thereby prolong the fighting.
A U.S. soldier searches a surrendering Japanese soldier. (National Archives)
Before Operation ICEBERG, psychological warfare operations against the Japanese had been something of a disappointment. On Okinawa, however, military resistance from civilians was negligible, and larger numbers of enemy soldiers gave up earlier in the campaign than had been anticipated. Admiral Nimitz's staff, which was largely responsible for ICEBERG psychological warfare planning, judged it to be the most successful program of its type during the Pacific war.
Based on experience gained from previous encounters with the Japanese across the reaches of the Pacific, Tenth Army planners also incorporated a vast amount of naval gunfire support in their preparations. From L-Day forward ground commanders carefully coordinated the fire of dozens upon dozens of naval rifles in support of the soldiers and marines ashore. The illumination rounds--"star shells"--these ships could fire was of special importance, given the Japanese penchant for attempting night infiltrations. As units of the Tenth Army moved southward across Okinawa the battleships followed them offshore, floating bases of mobile artillery that were called upon repeatedly throughout the campaign.
The close coordination of shipboard fire support was only one example of the interservice cooperation which, coupled with skillful small unit tactics, marked the success of the Ryukyus Campaign. That
cooperation also took the form of joint air and artillery support when conditions on the battlefield warranted. Army, Marine, and Navy planes provided close air support to Army and Marine ground forces interchangeably, especially as Japanese kamikaze air attacks eased after mid-May and during June, freeing more fleet aircraft for ground support missions.
Army and Marine artillery similarly supported one another's infantry as the American forces fought southward on Okinawa. Artillery battalions from all six divisions involved in the campaign were engaged wherever there was fighting. As infantry units rotated all across the front, these artillery battalions remained on line, with twelve Marine and Army corps artillery battalions reinforcing the twenty-four battalions assigned to the divisions.
By the time the battle for the Ryukyu Islands ended American forces had expended 97,800 tons of ammunition, most of that tonnage in artillery. Indeed taking into account the size of the invading force, the length of the fighting front, and the duration of the campaign, the invading force's concentration of naval, air, and ground fire unmatched in the history of warfare.
This awesome array of firepower was matched however, by the carefully prepared Japanese defenses on the island especially in the area centered around the Shuri heights. Here the Japanese 32d Army may well have created the most extensive network of caves and underground tunnel defenses with overlapping fields of covering fire ever faced by an opposing force. Far more elaborate than the trench systems used in World War I, the Japanese Army created a barrier that anticipated superior enemy assaults on the ground as well as sustained aerial and naval bombardments. Were it not for the gunfire from the assembled naval armada off the coast, the American infantrymen--even with supporting armor--would have stood little chance of making headway against such deeply dug-in defenses. But even the main batteries of the battleships, delivering broadsides at relatively close range, could not penetrate many of the enemy cave fortifications. No single supporting arm could overcome the elaborate complex dug into Okinawa's rocks and coral. Only the infantry, gradually moving forward with the support of artillery, armor, and engineers could eliminate the carefully prepared enemy positions.
Except during the last two weeks in May, when heavy rains prevented armor support of the infantry, the assault battalions could rely on American tanks, which on Okinawa were used almost exclusively in combined arms operations. The broken terrain of the island dictated the limited role that armor played and the opportunities for armor
mass and maneuver. Flamethrower tanks--the fifty-five specially equipped medium tanks of the 713th Tank (Armored Flame Thrower) Battalion were particularly vital to the GIs in gradually overcoming entrenched enemy positions.
The Japanese, knowing that they would face superior numbers and types of tanks, had developed an elaborate plan for engaging armored vehicles with hand-thrown demolition charges. Similar tactics had been successful for the Japanese on both Saipan and Iwo Jima. But, although such desperate techniques often were successful on Okinawa, they almost always failed when infantry covering fire was present. The only time armor attempted to operate without infantry support, in the 27th Division's assault on Kakazu Ridge, the result was a disaster. Tenth Army suffered 153 tanks destroyed' with many more damaged during the battle. In all, the casualty rate for American armored vehicles on Okinawa was high, approximately 60 percent.
In the end the campaign for the Ryukyu Islands consisted mainly of small unit actions, more often than not emphasizing combined arms tactics and individual initiative. Many of the key actions took place on the platoon or squad level, and in more than one instance the actions of an individual soldier decided the outcome. The battle of Okinawa, therefore, together with the earlier bloody struggle for Iwo Jima, ominously showed how difficult the final conquest of the Japanese home islands might be. Thus, a little more than a month after the campaign ended, it was with profound joy that the weary soldiers and marines who carried the fight through the mud and over the rough terrain of Okinawa learned that they would not have to face a final climactic battle. The Japanese formally surrendered on 2 September 1945, and the campaign Or the Ryukyus was the last major battle of World War II for the American soldier.
For those interested in the struggle for the Ryukyus, the most comprehensive treatments remain the two official histories of the campaign: Roy E. Appleman et. al., Okinawa: The Last Battle (1948); and Benis M. Frank and Henry I. Shaw, Jr., Victory and Occupation, vol. 5, History of U.S. Marine Corps Operations in World War II (1968). James H. Belote and William M. Belote, Typhoon of Steel: The Battle for Okinawa (1970) is highly recommended. See also Ian Gow, Okinawa, 1945 Gateway to Japan (1985); Thomas M. Huber, Japan's Battle of Okinawa, April-June 1945, Leavenworth Paper no. 18 (1990); Masahide Ota, This Was the Battle of Okinawa (1981); and Gordon Warner, The Okinawa War (1985).
HyperWar links to histories and documents related to the Ryukyus campaign are on the "Final Battle" page.
CMH Pub 72-35