The Sea Approaches and Coastal Waters
3rd September-31st December, 1939
The necessity for consistent experiments to determine some satisfactory method of destroying magnetic and acoustic mines cannot be too strongly emphasised. Extract from the Final Report on Mine Clearance in Home Waters. 15th September 1919.
THE sea approaches to these islands with which, in these volumes, we are principally concerned comprise the waters to the west of our own and Eire's western shores; for it is to and from that direction that the greatest proportion of our shipping passes on its journeys between Britain and ports all over the world. Because so many ships come through these focal waters it was natural that the enemy should concentrate his onslaught there and that the continuous struggle, later called the Battle of the Atlantic, should largely have been waged in these Western Approaches from the Atlantic.1 During the period with which we are now concerned shipping could approach this country from the west by either of two general routes. The first passed north of Ireland and led to the North Channel and into the Irish Sea from the north; these waters were called the North-West Approaches. The second passed south of Ireland and led to the English Channel, the St George's Channel and into the Irish Sea from the south; these were known as the South-West Approaches.
It will be convenient, however, in the pages which follow to consider the defence of shipping in the sea approaches and in our coastal waters together, since to separate the two, when no clearly defined boundary existed between them, would be artificial. It is also proposed to deal in turn with each of the three main weapons used by the enemy to attack our shipping. These were the mine, the submarine and aircraft.
Before we consider the enemy's offensive against our shipping the counter-measures taken by the Admiralty must be told. The chief of these was, of course, the convoying of merchant ships, and it has
been seen that arrangements for its introduction had been carried to an advanced stage well before the outbreak of war.1 The Admiralty has, at different times, given various definitions to the expression 'convoy', but modern naval opinion has gained acceptance for the view that it should be defined as one or more merchant ships sailing under the protection of one or more warships'. In other words two requirements must be fulfilled before ships can be said to be sailing in convoy--they must be operated in an organised group and they must be provided with an escort. It is in this sense that the term is used throughout these volumes. It is unfortunate that the description 'unescorted convoy' was used during the early months of the war; it is now held that such an expression is a contradiction in terms and that, if no escort is present, the ships, though sailing in an organised group, cannot be called a convoy. To arrive at a fair and proper assessment of the results achieved by the convoy system the losses inflicted on such groups of ships must be excluded from every analysis of shipping sunk while in convoy, and this has been done throughout these pages.
The practice of escorting unarmed or lightly armed merchant ships by warships is of very ancient standing. In particular it was widely practised by this country and its enemies during the European wars of the seventeenth and eighteenth centuries. After the Napoleonic Wars convoy seems to have fallen into disfavour. The introduction of steam and the vast expansion in the amount of commerce carried and the number of ships employed to that end were certainly important factors in bringing about this change of opinion. In retrospect it does, however, seem curious that the principle of providing safe passage against all forms of sporadic war on trade by close escort, on the soundness of which history can provide innumerable examples, should have been lost to sight equally with the practice of making the close escort really effective by assembling and sailing merchant ships in convoy. The immediate success of the measure from 1917 until the end of the First World War proved that modern developments had not made the centuries-old practice obsolete.
The first convoy, consisting of eight important ships sailing from Gibraltar to Capetown, actually left on the 2nd of September before war had been declared. Three days later a troop convoy consisting of eleven transports with reinforcements for numerous bases and overseas garrisons left the Clyde for Gibraltar escorted by the battleship Ramillies and eight destroyers. These were, however, not mercantile convoys in the strict sense. A mercantile convoy system runs at regular intervals from the same port of assembly, and the number of days between successive convoys is called the 'convoy cycle'. The
Sept 1939 -- April 1941
Principal Atlantic and Home Waters Convoy Routes
showing approximate zones of close anti-submarine escort
earliest mercantile convoys of the war were the east coast convoys between the Thames and the Firth of Forth (F.N.) or vice versa (F.S.). They started on the 6th of September and were initially sailed in each direction every second day.3 These convoys were the special responsibility of the Rosyth Escort Force--composed of ships with good anti-aircraft as well as anti-submarine armaments. On the 7th of September outward-bound ocean convoys were started. One series (O.A.) sailed every alternate day down-Channel from Southend and another (O.B.) left Liverpool, generally on the same day, and steamed south through the Irish Sea. During the first phase of the war these outward ocean convoys were only given close escort as far as Longitude 121/2° West; west-bound ships dispersed two days after the escorts had left And continued to their destinations independently. The destroyers generally waited at the rendezvous to bring back the next inward convoy. South-bound ships from the O.A. and O.B. convoys were formed into Gibraltar (O.G.) convoys when they reached a position off the Scilly Islands and proceeded with an ocean escort only, until they were met by anti-submarine vessels from Gibraltar to the west of the Straits.
The first homeward-bound convoy sailed from Freetown, Sierra Leone (S.L.), on the 14th of September and the next day a fast convoy (K.J.F. 1) left Kingston, Jamaica, for home. These convoys from Jamaica were not continued for long but were absorbed into the Halifax convoys. The first of the famous series of Halifax convoys (H.X. 1), around whose passages the Battle of the Atlantic was largely to revolve, sailed under Canadian local escort on the 16th of September, followed on the t 9th by the first of the fast convoys from the same port (H.X.F. 1), while the first homeward convoy left Gibraltar (H.G. 1) on the 26th of September.
The Norwegian convoys from Bergen to Methil in the Firth of Forth (H.N.) and vice versa (O.N.) were not started until the first week of November, and their escort and safe passage was made the responsibility of the Commander-in-Chief, Home Fleet.
Map 9 shows the more important convoy routes operated during the first eighteen months of the war. In spite of the rapid organisation of a large number of convoys on the outbreak of war many ships already at sea could not be included in convoys during their current voyages. Moreover it had always been intended that ships able to steam over a certain speed (fifteen knots in the North Atlantic), and
also those unable to reach a speed of nine knots, should not be ordered into convoy. They would, instead, merely be given a route to follow and would sail independently. It was among the ships still sailing un-convoyed and the groups of ships sailing in company but for whom no escorts could be found that the U-boats found easy targets during this phase. For example, a group of unescorted ships from Jamaica was attacked in the Western Approaches on the 13th of October and lost two ships; four days later a similar group, homeward-bound from Gibraltar, was attacked off Cape Finisterre and three of their number were sunk. Losses among properly convoyed ships were very few. By the end of the year 5,756 ships had been sailed in them and only four had been sunk by submarines.4 In spite of the chronic shortage of escort vessels the success of the system was immediately proved; it paid tribute not only to the careful planning by the Admiralty but to the work of the Naval Control Service staffs at home and abroad and to the willing co-operation of the owners and masters of the merchant ships themselves.
The organisation of convoys abroad was made the responsibility of the naval Commander-in-Chief of the theatre, and he was given the necessary powers to enforce Admiralty decisions in this respect. Thus it was on Admiralty instructions to the Commander-in-Chief; America and West Indies, and North and South Atlantic stations respectively, that the Kingston, Gibraltar and Freetown homeward convoys were started in September.
Experience of the system was bound to show where improvements could be made; and the possibility of making such improvements was kept constantly in the minds of the officers of the Trade Division of the Naval Staff. Thus the assembly port of the southward-bound east coast convoys was, at the end of November, altered from the Forth to the Tyne with the object of speeding the flow of shipping on the east coast, and ships proceeded to the Tyne independently. But losses among these independents became heavy and, in February 1940, the convoy system had to be extended to the Forth again.
It has often been said that the convoy system is bound to delay shipping. Superficially this is true, because the speed of a convoy must be the speed of the slowest ship, and loaded ships may have to wait before their convoy is ready to sail. Moreover, when a large number of ships arrives at the same port together the unloading arrangements may be unable to cope with them all. But there are certain other aspects of the problem which tend to show that delays caused by the convoy system have, in the past, been exaggerated and that, when the degree of danger is considerable, it is more economical in terms of tonnage saved to convoy the ships. In the Atlantic it was
certainly the case that losses among independently-routed ships were so much higher than among those convoyed that the wider use of convoy would, in terms of tonnage saved, have been more economical throughout the recent war. Examples also exist where independently-routed ships steamed much faster than the convoys, but made slower passages because they were so widely diverted from dangers. In fact it now seems that, except in waters where the danger to shipping is slight, it is better to convoy than not to do so. While a war is actually in progress it is bound to be difficult to reach a correct decision on this matter. But it seems clear that failure to convoy when one should have done so is likely to produce worse effects than convoying ships when one need not have done so.
To eliminate all possible causes of delays to our shipping was, of course, a continuous aim of the Admiralty and Ministry of Shipping. During the early days the Cabinet considered the same matter several times. Thus on the 10th of November the First Lord reported to the Cabinet his proposals for a number of measures to reduce delays. Such measures generally involved some reduction in the protection afforded to the ships, and to balance protection against speed of turning ships round became an important issue of policy. By the 17th of November the Ministry of Shipping considered that the initial difficulties were being satisfactorily overcome, but the position remained difficult because, even if imports were reduced from the normal peace-time figure of 60 million tons annually to a total of 47 million tons by rationing and other emergency steps, some 11 million tons of this figure would have to be imported in neutral ships, the chartering of which in time of war is never easy and always expensive.
Troop convoys were always given very strong escorts, drawn generally from the Home Fleet, and the main units of that fleet always covered their progress. Mention of such operations was made when we considered the operations of the Home Fleet during this initial phase.5
One of the difficulties encountered in these early days was to persuade neutral shipping to sail in our convoys. This problem also came before the Cabinet, and in November the First Lord suggested that we might get control of all free neutral shipping by charter or other means, and so extend the advantages of convoy to such shipping. At the end of November the First Lord pointed out that, whereas our own losses were steadily decreasing, those suffered by neutrals were rising. But this problem was not finally solved until virtually all European neutral shipping was eliminated by Hitler's 1940 land campaigns. Thereafter arrangements were made to control
much of the shipping of occupied countries and so include it in our convoys.
The closing of the English Channel by a mine barrage across the Straits of Dover formed, as has been seen, part of the naval war plans and aimed both at securing the transports carrying the British Expeditionary Force to France from attack by enemy submarines or flotilla vessels, and at preventing the use by enemy submarines of the shortest route from their bases to the focal areas of our trade in the Western Approaches. The operation was carried out under the orders of the Vice-Admiral, Dover, by the minelayers Adventure and Plover augmented by the train ferries which were requisitioned and converted for the purpose.
The first of the three stages into which the completion of the barrage was divided was the laying of three lines of shallow and two of deep mines to the east from the Goodwins towards the Belgian coast. A secret channel was left off the Goodwins for use by our own ships.6 This was started on the 11th of September and the minelayers laid about 3,000 mines during the six following days. They were escorted by the anti-aircraft cruiser Cairo and the 19th Destroyer Flotilla, which had been lent from the Channel Force and the Nore Command respectively, and were covered by the Humber Force.
The second stage was the laying of a deep minefield between Folkestone and Cape Gris Nez which, since it was less urgent than the first, was not started until the 25th of September. By the 23rd of October 3,636 mines had been laid and it was completed. The third and final stage consisted of the placing of a double system of indicator loops between the two minefields to detect any U-boats which might attempt the passage of the Straits.7
The Dover barrage undoubtedly accomplished its purpose. Only one U-boat is known to have passed through the Straits successfully, and that was on the night of the 11th-12th of September before even the first stage of the barrage had been completed. In October two enemy submarines were blown up and destroyed in the minefields and a third ran aground on the Goodwin Sands. She, too, had almost certainly been mined in the barrage. Thereafter the enemy abandoned the attempt to send his coastal submarines by the shortest route to the focal areas of the central and western Channel --the waters through which all shipping approaching or leaving the southern ports of Britain must pass.
The laying of the Dover barrage was the only defensive minelaying operation carried out in the first weeks of the war, though a declared area between the Humber and the Tyne, about twenty miles wide and a like distance offshore, was proclaimed on the 23rd of
British and German Declared Mine Areas, 1939-40
September.8 This was, in fact, the genesis of the east coast mine barrier, whose purpose was to protect our coastal shipping against incursions by enemy surface vessels or submarines. No mines were, however, actually laid in these waters until the end of the year.
On the 19th November the First Lord placed before the Cabinet the Admiralty's proposal to lay a defensive mine barrage right across the North Sea, extended if possible to the Norwegian coast, with the object of completely closing the exits from that sea to enemy surface vessels and submarines. This proposal was, in fact, a repetition of the Northern Barrage of the closing months of the First World War. It required the laying of 181,000 mines at a cost of nearly £20 millions, and it was estimated that it would take two years to complete. Though the First Lord felt some misgivings regarding the expenditure of so prodigious an effort on a purely defensive measure, he finally commended the scheme and, on the 30th November, the Cabinet approved the start of the necessary preparations.9 The Foreign Office meanwhile pointed out that the Norwegian Government was most unlikely to agree to the closure of the eastern end of the barrier--which had not been accomplished until two months before the end of the 1914-18 war--and that its effectiveness was therefore likely to be vitiated by the enemy's ability to continue to use Norwegian territorial waters. The Northern barrage proposal was thus intimately connected with stopping the enemy's use of the inshore route along the Norwegian coast, by his iron ore ships from Narvik in particular. This enemy traffic was, in fact, perfectly legitimate; but other uses to which he placed this geographical peculiarity of the Norwegian coastline were certainly less so. The legality of the iron ore traffic passing to Germany by this route did not, however, remove the natural desire of the Admiralty to bring it within our blockade. The First Lord repeatedly pressed on his colleagues the view that it should be stopped by mining the inshore route as a reprisal for German infringements of Norwegian neutrality. The Cabinet, however, refused to sanction the Admiralty proposals. Thus did the question of the control of the coastal communications off Norway begin to play a big part in the political and strategic thoughts and plans of both sides from the earliest days of the war.
Our offensive minelaying campaign, which was to last throughout the whole war and take on many and varied forms, started very soon after war was declared. To augment the forces available for this purpose two destroyers, the Esk and Express, were converted to minelayers in August 1939, and placed under the orders of the Commander-in-Chief, Home Fleet. A mined area in the Heligoland
Bight was notified by the Admiralty on the outbreak of war, and mines were laid inside its limits by the destroyers on the night of the 9th-10th of September in positions which were believed to lie on the routes used by the German major warships when proceeding to and from their North Sea bases. However, after a second lay had been carried out, doubts arose regarding both the accuracy of the lays and the adequacy of our intelligence on enemy movements; the programme was therefore suspended until both had been improved. The minelaying flotilla was not again employed in an offensive rôle until the middle of December. By that time it had been reinforced by the destroyers Ivanhoe and Intrepid. The flotilla laid 240 mines in the mouth of the River Ems on the night of the 17th-18th of December without meeting any enemy opposition, and that was the last offensive minelaying operation of 1939.
The enemy meanwhile had not neglected either defensive or offensive minelaying. Like ourselves he notified a declared area in the North Sea. Its limits enclosed a rectangle, stretching north from Dutch waters for about 180 miles, and 60 miles wide. It overlapped with the British declared area.10 His object was to bar the approaches from the west to his ports and bases on the North Sea coast.
By the end of the year, the Admiralty considered that the swept channels and the areas actually mined by the enemy were known accurately enough. It was accordingly decided to use the minelaying flotilla to place some small fields within the enemy declared area in what were believed to be his swept channels. A number of operations to this end were carried out early in the new year, and it is now known that an enemy torpedo-boat was blown up on one of these fields. This, however, was the only success achieved.
Turning now to the enemy's offensive minelaying, we come to the first important tactical success which must be credited to him. All the mines laid by our own forces in the operations already described were of the contact type and conformed to the requirements of International Law. The enemy had, however, developed and put into production the first of a long series of mines which can be broadly described as being of the influence type, whose explosion was caused not by actual contact with a passing ship but by the influence of a ship's magnetic field on the mechanism of the mine.
The Hague Conventions only refer to contact mines; but it could reasonably have been claimed by the Germans that the magnetic and other influence--type mines conformed to International Law--if they had laid them only in declared areas. But, from the start of their offensive mining campaign, they actually sowed all types of mines wherever they were considered likely to achieve results. It was in the
manner in which they were used rather than in the use of mines of the influence type that the illegality of the enemy's methods lay. The magnetic mine was, however, by no means a new weapon of war. Such mines had been made by ourselves during the First World War, and we actually laid some in the mouth of the River Scheldt and off Zeebrugge in 1918. That type of magnetic mine was not, however, successful and development was therefore pursued along different lines until, by 1939, the British standard magnetic mine was ready for production. Meanwhile counter-measures were being studied, and an Admiralty committee had been charged with investigating the protection of ships against such weapons. In July 1939 the first trials were done in the Solent with a magnetic sweep. It was a somewhat clumsy affair, but was reasonably successful against our own mines. It was difficult, if not impossible, to design in advance a sweep capable of exploding mines fired by all the numerous variations in magnetic influence which an enemy might employ. We had first to discover the 'firing rule' of the mines used against us. 'Mine destructor ships', which would carry a large magnet in their bows and explode mines ahead of themselves, were also considered by the Admiralty; but the construction of one was struck out of the 1939 Navy Estimates as 'unwarranted expenditure'. They were used later, as will be told shortly, but neither we nor the enemy found them to be successful.
The position on the outbreak of war was, therefore, that the entire British minesweeping force then in service, and the whole of the equipment planned and ordered for the large numbers of auxiliary minesweepers to be requisitioned and converted, were designed only to deal with moored contact mines; but research and development work had been carried to a point where production of a sweep could be started as soon as we became possessed of the necessary information regarding the type of magnetic influence required to fire the enemy's mines. It was in the first week of war that sinkings off the east coast raised the suspicion that the Germans were using ground mines of the influence type, as well as contact mines. This was confirmed when, on the 16th of September, the S.S. City of Paris was damaged by an under-water explosion but her hull was not penetrated.
The enemy was, perhaps, justified in claiming that we had been 'tactically and technically surprised'; but he was soon to discover that, thanks to the research work carried out before the war, the measure of surprise which he had achieved was not as great as he believed. And, happily for ourselves, he was not in a position to exploit his success to the uttermost, because on the outbreak of war his stock of magnetic mines was small. Meanwhile in the Admiralty a special staff had been placed under Rear-Admiral W. F. Wake-Walker to hasten the production of counter-measures in collaboration
with the mining department of H.M.S. Vernon, the torpedo school at Portsmouth, and commercial firms whose work lay in that field.
On the 23rd of November the period of groping for knowledge in the dark ended with the recovery of a complete mine off the mudflats of Shoeburyness, where it had been dropped by an aircraft. It was 'dissected at great personal risk by Lieutenant-Commander J. G. D. Ouvry. We then discovered that the German mine was fired by a change of magnetism (as opposed to rate of change in the British mine) in the vertical (as opposed to the horizontal) field; and that it required the passage of a ship built in the northern hemisphere, which would therefore have its north magnetic pole downwards.11
The enemy realised that we were at first unable to sweep his mines and immediately planned a great increase in production. But it was too late, since before that could be achieved we were possessed of knowledge on which the design of the 'LL Sweep' could be firmly based, and, although a great production effort still had to be made, defeat of the magnetic mine was then in sight.
On the 20th of October the first success in exploding a magnetic mine harmlessly was obtained with an extemporised sweep. But by the end of that month we had lost nineteen ships of 59,027 tons by mines;12 and many of them had been sunk on the five magnetic fields laid off the east coast and in the Thames estuary.
In November matters got worse and the Nore Command had great difficulty in finding and marking safe channels in the Thames estuary. At one time, in the middle of the month, only one of the three deep-water channels into the river was open, and it seemed that the enemy might succeed in completely stopping the flow of traffic in and out of the Port of London. Fortunately this did not occur, but twenty-seven merchant ships of 120,958 tons and the destroyer Blanche were sunk by mines during the month and many more damaged--including the cruiser Belfast and the minelayer Adventure. Diverting ships from ports off which mines were known to have been laid was not very successful and many ships were sunk in waters known to have been mined.
In the middle of November enemy aircraft started to drop mines, but they lacked the means of fixing their positions accurately and so contributed less than might be expected to augmenting our difficulties. Accurate minelaying by enemy submarines and surface
'Fleet Minesweepers at work in the Straits.' By Leslie Cole.
(National Maritime Museum)
'A Minesweeper.' By Charles Cundall.
(National Maritime Museum)
An East Coast convoy, 1940, with an Anson aircraft of Coastal Command in the foreground.
vessels, with contact as well as magnetic mines, had been greatly assisted by the fact that coastal lights were kept burning for the benefit of our own vessels; on the 21st of November lights in the Thames estuary were therefore extinguished, and all traffic west of a line between the Downs and Orfordness was stopped during the hours of darkness. This measure brought immediate relief to the Thames approaches.
Meanwhile, the extemporised measures, which included sweeps, skids, mine destructor ships and specially converted Wellington aircraft, continued their endeavours, though only with occasional successes. The mine destructor ships, of which the Borde was the first, proved very vulnerable to damage by the mines they exploded. The minesweeping aircraft scored some successes, but suffered from the weakness that they could only sweep a narrow path which could not be marked. Both were abandoned as soon as better means became available, though the aircraft later proved valuable in assisting to keep the Suez Canal clear of magnetic mines.
Energetic measures were taken by the Admiralty to reduce the magnetism of the ships themselves. Though this could not make them immune from magnetic mines and did not in any way reduce the need to sweep the mines themselves, it did increase the confidence with which the crews of merchant vessels sailed through waters known to be mined. A special department was formed to deal with 'de-gaussing' all our warships and merchantmen. This involved not only an enormous and immediate demand on manufacturers of electric cable, but placed an additional strain on our overburdened shipyards. The effort involved in carrying out the programme was comparable in size and scope to fitting all our Merchant Navy with defensive armaments.13 But whereas the latter had been provided for, and the necessary measures put in hand well before the outbreak of war, a similar organisation for 'de-gaussing' or 'wiping' the ships, and for keeping that part of their war-time equipment efficient, had to be built up from nothing. It was gradually extended to all the major ports of the world.
In December the enemy switched his chief minelaying activities from the Thames estuary to the narrow channels off the Norfolk coast through which the east coast convoys had to pass. Pressure on the Nore Command minesweepers and on the organisation for the control of shipping continued severe, though the general outlook was less critical than in the preceding month. Thirty-three merchant ships of 82,712 tons were sunk by mines and eight others damaged, but there was a decline in the number of magnetic mines laid, owing, we now know, to the enemy's stocks having run low. It was indeed
fortunate that the enemy had only manufactured some 1,500 by the time war broke out, and was able to produce very few more during the first months of the war. On the other hand, his stores had held over 20,000 contact mines when war broke out and it was, therefore, on the laying of that type of mine that his campaign chiefly depended during the early months. The losses and dislocation caused by magnetic mines were, in fact, out of all proportion to the 47o mines actually laid during the first three months of the war.
On the night of the 12th-13th of December five enemy destroyers, covered by the light cruisers Leipzig, Nürnberg and Köln laid a large contact field off the Tyne. A Bomber Command striking force searched for the enemy without success but, at dawn on the 13th of December, the submarine Salmon (Lieutenant-Commander E. O. B. Bickford), on patrol in the Heligoland Bight, sighted the force. Nine days earlier she had sunk U.36 with torpedoes. Now she added to the success of a remarkable patrol by hitting both the Leipzig and Nürnberg. Unfortunately heavy counter-attacks prevented her making an enemy report until five hours later, which delay improved the chances of the damaged ships making good their escape. Two days later the submarine Ursula sighted the damaged Leipzig limping south along the Danish coast and attacked unsuccessfully, though her torpedoes sank one of the escorting flotilla vessels. The Nürnberg was out of action until May 1940 and the Leipzig until the following December, and even after that date could not be restored to full operational use, but was only employed on training duties. This bold minelaying operation by the enemy therefore ended with a substantial success to our submarines and a serious loss to his own cruiser strength--regrettable though it was that neither of the ships attacked was actually sunk.
To summarise this first phase of the minelaying campaign, the enemy had caused us substantial losses in the first four months of war, totalling seventy-nine merchant ships of 262,697 tons, and had dislocated the flow of our coastal shipping very seriously. One countermeasure which was denied to us, on account of the restrictive rules on air bombardment then in force, was to bomb the seaplane bases from which his minelaying aircraft were known to work, or the naval bases used by his submarine and surface minelayers. On the 12th of December the Air Ministry proposed to maintain bomber patrols over these bases; but the Cabinet would not permit bombs to be dropped. Yet the whole enemy campaign had been contrary to International Law and the Cabinet had only very recently introduced control of enemy exports in retaliation for these illegal methods of waging war.
To turn now from the enemy's minelaying campaign to the first phase of the U-boat war on our merchant shipping, it has been seen
that his full available strength of ocean-going U-boats had sailed for the Atlantic before the outbreak of war, and that his coastal boats had been sent to patrol for short periods of about fourteen days in the North Sea and at the eastern end of the Channel.14 On the 7th of September there were twenty-one ocean-going boats disposed from the northern entrance to the Irish Sea as far south as the Straits of Gibraltar. Such an effort could not, however, be sustained for long, and by the middle of the month some boats had returned to their home bases. On the 18th only eleven remained on patrol in the Atlantic.
But it was to be expected that such a large initial effort should cause appreciable losses in the first weeks of the war, because the Admiralty's control of merchant shipping had not yet had time to take full effect, and the organisation of convoys and other protective measures were still in their infancy. The first casualty occurred on the day war was declared, when the Donaldson liner Athenia was sunk without warning by U.30 in flagrant disobedience to Hitler's orders to wage submarine war only in accordance with the Hague Conventions. The Germans investigated the Athenia incident fully and decided to keep the truth secret. No disciplinary action was taken against the culprit, who was held to have 'acted in good faith' in the belief that the ship was an armed merchant cruiser. They never admitted responsibility for the sinking.
Hitler's original orders to the German Navy, including the U-boats, to wage war only in accordance with the Prize Regulations, were not issued in any altruistic spirit but in the hope that, after Poland had been crushed, Britain and France--and especially the latter--would make peace. As soon as it was realised that this hope was vain, removal of the restrictions on the methods of waging war at sea started. It will be appropriate to review now the various stages through which this process passed.
On the 23rd of September, Hitler, on the recommendation of Admiral Raeder, approved that 'all merchant ships making use of their wireless on being stopped by U-boats should be sunk or taken in prize'. As the immediate despatch of a wireless signal in such circumstances was included in the Admiralty's instructions to merchant ships and was essential--if for no other reason--to the rescue of their crews, this German order marked a considerable step towards unrestricted warfare. Next day, again as a result of representations by Raeder, the order forbidding attacks on French warships was cancelled. On the 30th of September observance of the Prize Regulations in the North Sea was withdrawn; and on the 2nd of October complete freedom was given to attack darkened ships encountered off the British and French coasts. Two days later the Prize Regulations were cancelled in waters extending as far as 15° West, and on
the 17th of October the German Naval Staff gave U-boats permission 'to attack without warning all ships identified as hostile'. The zone where darkened ships could be attacked with complete freedom was extended to 20° West on the 19th of October. Practically the only restrictions now placed on U-boats concerned attacks on liners and, on the 17th of November, they too were allowed to be attacked without warning if 'clearly identifiable as hostile'. Although the enemy this time carefully avoided the expression 'unrestricted U-boat warfare', it can therefore be said that, against British and French shipping, it was, in fact, adopted by the middle of November 1939. Neutral shipping was also warned by the Germans against entering the zone which, by American neutrality legislation, was forbidden to American shipping, and against steaming without lights, zigzagging or taking any defensive precautions;15 it was not until the following year that more drastic action was threatened.
Though the change from full observance of the Prize Regulations to virtually unrestricted U-boat warfare was made cautiously in order to avoid trouble with the United States or offending the 'friendly neutrals'--Russia, Japan, Italy and Spain--it is to be remarked that, in the First World War, it was not until the 31st January 1917--after nearly two and a half years of war--that the Germans reached a stage which, in the second war, took them only a few months to travel. It is impossible to avoid the conclusion that Admirals Raeder and Dönitz and the German Naval Staff had always wished and intended to introduce unrestricted warfare as rapidly as the political leaders could be persuaded to accept the possible consequences.
To return to the operations by the U-boats, in spite of the advantage gained by the dispositions taken up before war broke out, all did not go well with Dönitz's plans. In October the first attempt at co-ordinated attacks by several boats against the Gibraltar convoys failed completely; an intended thrust into the Mediterranean also came to nothing. In the following month a second attempt at co-ordinated attacks fared little better than the first. Mines laid by the smaller boats in the approaches to our ports on the west as well as on the east coast sometimes achieved important results; but these boats accomplished little in direct attacks on shipping.
The use by the U-boats of the northern route to the Atlantic, as the necessary consequence of our closure of the Dover Straits by the mine barrage already described, led to frequent sightings by aircraft of Coastal Command flying the normal North Sea reconnaissance patrols. The naval and air staffs at the Command's headquarters had been developing a system of special air patrols based on careful study of the probable times of arrival of U-boats in certain fairly well
defined areas. They were designed to harry the U-boats while on passage. This led, before the end of the year, to a full realisation of the great contribution which aircraft could make to the defence of merchant shipping against submarine attack--once an effective antisubmarine weapon had been provided. On the 13th of November a directive was issued to Coastal Command that action against U-boats was to be regarded as of equal importance to reconnaissance duties. This directive forms something of a landmark in the development of the great structure of sea-air co-operation. But progress in the employment of aircraft against U-boats was bound to be slow, since not only had Bomber and Coastal Command aircrews received practically no pre-war training in this highly specialised form of warfare, but a suitable weapon was still lacking. We shall return to that subject later. For the present it is only necessary to remark the complete lack of success obtained by air attacks on U-boats during these early months, and to record that conclusive evidence of the ineffectiveness of the weapons then used was soon received through misidentification of our own submarines by friendly aircraft which, on two occasions, bombed them without inflicting any damage.
Before leaving the first phase of the U-boat war, it will be appropriate to consider two attacks which took place in September on our aircraft carriers. The first was against the Ark Royal which on the 14th of September was temporarily detached from the Home Fleet and operating to the west of the Hebrides as part of a hunting group against U-boats. The torpedoes missed astern of the aircraft carrier, whose escorting destroyers promptly counter-attacked, sank U.39 and captured her crew. But the escape of this important ship had been narrow, and such good fortune was not to be repeated when next a U-boat encountered a fleet carrier in search of the same quarry. On the 12th of September the enemy's wireless intelligence service estimated correctly that the Courageous was working in the Western Approaches, but no accurate knowledge regarding her movements was deduced. The War Diary of U.29 leaves no doubt that the sighting of the aircraft carrier at 6 p.m. on the 17th of September was entirely unexpected. The U-boat was, in fact, almost at the end of her patrol and was proceeding, as a final operation, to try to intercept a convoy reported by another U-boat, when she sighted the Courageous through her periscope. It was not until nearly two hours later that an attack could be made, and then only because the carrier suddenly altered course to 'fly on' her aircraft and so placed the U-boat in a favourable attacking position. Moreover, the Courageous was at the time screened by only two destroyers, since the other two comprising her escort had been detached to the assistance of a merchant ship which had been attacked. An unlucky chain of circumstances thus placed this valuable ship in a position of great
danger, which Lieutenant Schuhart of U.29 exploited to the full. At 7.50 he fired three torpedoes at a range of less than 3,000 yards and two of them hit. The Courageous sank in fifteen minutes with the loss of her Commanding Officer (Captain W. T. Makeig-Jones) and 518 of her complement. U.29, though heavily counter-attacked until midnight, successfully returned to her base.
As a result of these attacks the Cabinet advised the withdrawal of fleet aircraft carriers from submarine hunting work. Our weakness in that class of ship, of which only the Ark Royal was of modern design, and the obvious danger to which submarine hunting would expose them, now makes it seem surprising that they should have been risked on that type of duty. It is possible that the understandable desire at once to take the offensive against the U-boats, and confidence in the protection which asdic-fitted destroyers would provide to heavy ships, both contributed to acceptance of the risks involved.
To summarise the results achieved in this first phase of the U-boat war, our merchant ship losses were as follows:--
Table 5. Allied Merchant Ship Losses, September--December 1939
September 1939 41 ships 153,879 tons October 1939 27 ships 134,807 tons November 1939 21 ships 51,589 tons December 1939 25 ships 80,881 tons TOTAL 114 ships 421,156 tons
Of the 114 ships sunk only twelve were in convoy; five more were stragglers from convoys when they were sunk. In accomplishing these results the enemy had, however, lost nine U-boats--about one-sixth of his total strength.16 From the Admiralty's point of view the results achieved were by no means discouraging. But it was realised that, as the enemy's war construction programme gathered way, the campaign was bound to be intensified and that this first phase was little more than a preliminary skirmish between the opposing forces. During the last two months of the year the mine had actually surpassed the U-boat as the principal cause of our shipping losses.
Now that we have reviewed the first phase of the enemy's assault on our seaborne trade by mine and submarine, it remains to consider the start of his use of the air weapon for similar purposes. It will be remembered that the Naval Staff had, before the war, held the view that such attacks would be countered by the normal and proved methods of defending merchant shipping, such as the use of convoy, and had considered that the weapons mounted in the escort vessels
would provide adequate defence.17 The Air Staff had been sceptical on this matter, but the result had been that provision for the air defence of shipping had not been given high priority. Offensive action against enemy forces of all types which might attack our shipping was placed third and last in priority for the allocation of Coastal Command's exiguous forces. Thus not only were no aircraft available for that purpose on the outbreak of war, but no training in protecting shipping against air attack had been carried out between the two services concerned. Nor had the responsibility for counter-measures to air attacks on our shipping been clearly defined or firmly placed. That the chief reason for this state of affairs was the too-sanguine outlook of the Naval Staff towards the air defence of both warships and merchant shipping now seems clear. The pre-war statement of one of the Committee of Imperial Defence's sub-committees that 'the problem of the protection of merchant shipping from air attack is at present unsolved' was rapidly substantiated.
It was not until the 1st of August 1939 that the Committee of Imperial Defence finally sanctioned the formation of four Trade Defence squadrons to act as close escorts to merchant ships sailing between Southampton and the Firth of Forth when more than five miles from the coast--the limit of radio-telephone communications between Fighter Command Sector Headquarters and the single-seater fighters of that command--and on the outbreak of war there was little likelihood of these squadrons being ready before the following year.18 However, when the enemy began to attack east coast shipping from the air in October, the formation of the four squadrons--Nos. 235, 236, 248 and 254--all of which were equipped with the fighter version of the Blenheim bomber, was hastened and all were formed on the 17th of that month.
The allocation of the responsibility for controlling these four squadrons proved difficult. Though the Admiralty and Air Ministry had agreed before the war that protection of shipping was among the responsibilities of Coastal Command, it was now realised that the coastal convoys constituted a special case. Fighter Command was already responsible for the defence of our ports and bases, and so of any shipping which might be within their limits, and its aircraft could be expected to afford some security to ships sailing within a few miles of the coast. It was accordingly decided that air protection of the coastal routes was, in principle, an extension of the existing zone of cover provided by Fighter Command, and it was to that command that the four Trade Protection squadrons were therefore initially assigned.
This arrangement was, however, of short duration, partly because
the Blenheim fighter was not well suited to the work and partly because aircraft of that type were constantly in demand for other maritime duties, such as armed long-range reconnaissance or protection of the fleet at sea. Neither of these requirements were responsibilities of Fighter Command, and both were new commitments for Coastal Command. The only way of meeting them was to divert the Blenheim squadrons to these duties, which soon came to absorb virtually the whole of their capacity. It was, therefore, only logical that they should be controlled by the command within whose sphere lay the greater part of their work. In December they were temporarily transferred to Coastal Command and in February 1940 the transfer became permanent. This, however, left the responsibility of protecting coastal shipping with Fighter Command, but using the short-range aircraft of the Air Defence of Great Britain (A.D.G.B.) organisation instead of the longer-range Blenheim fighters.
It was on the east coast that these problems first had to be faced. Though the enemy's air attacks on shipping were initially inaccurate and caused little damage, it was plain that the moral effect on the crews of slow and defenceless coasting steamers, fishing trawlers and even light vessels--all at that time practically unarmed--might soon become serious. Moreover these early attacks could but be regarded as harbingers of a more intensive assault of this nature on our coastal shipping. By the last month of the year they had, in fact, become more frequent and effective and ten small ships totalling 2,949 tons were lost from this cause in December.
As these arrangements were gradually evolved, Fighter Command's aircraft began to work from coastal stations between Norfolk and the Moray Firth and, in order to be able rapidly to send out aircraft in response to calls for help, each station kept watch on the wireless frequency used by any convoy which might be passing through its sector. In the spring of 1940 Fighter Command's organisation was extended to the east and north to improve the protection afforded. Calls from shipping more than twenty miles from the coast were at first answered by any Coastal Command aircraft which might be available, but in May 1940 Fighter Command's responsibility was extended to forty miles offshore. All calls from shipping closer in were answered by Fighter Command aircraft from the nearest station.
It was not to be expected that this newly-evolved system would always be effective, and the frequent arrival of the fighters after the bombs had been dropped resulted in demands for constant cover to be provided over the convoys. This requirement could not easily be met from the forces then available to Fighter Command; and such a system ran counter to the principle of control of fighter interception from Group and Sector Headquarters, on which the whole A.D.G.B.
organisation was founded. Not until February 1940 was a daily routine of fighter cover over the east coast convoy route agreed to by Fighter Command.
The difficulties encountered over protecting coastal shipping from air attack have been told in some detail, because they were brought about through failure to foresee such a necessity in time of peace and to make proper provision for it in the war plans. Though it is unlikely that, even had the requirement been foreseen, more, and more suitable, aircraft and more weapons could have been allocated to that purpose before the outbreak of war, the various spheres of responsibility could have been defined, the necessary organisation set up and a certain amount of tactical training carried out. As it was, all of this had to be learned from experience gradually and often painfully accumulated after the outbreak of war.
But the arrangements described above, though largely extemporised and, at this time, often unsuccessful, have considerable historical interest because they were the genesis of a world-wide system of protecting ocean as well as coastal shipping from air attack. The final answer lay in the control of the fighter aircraft from the ships which they were protecting--for it was the ships which generally obtained the first visual or radar warning of impending attack. A long road was, however, to be travelled from the early arrangements described in the preceding paragraphs to the institution of a co-ordinated system of 'Fighter Direction' from warships--as it was called later. It was this method which finally proved the answer to the protection of ships from air attack. The whole art of fighter direction depended on efficient radar warning sets in the ships and efficient radio-telephone communications from the ships to the aircraft, neither of which existed in the early days. The need was recognised in naval circles first, for it was the ships which were attacked and could not defend themselves; but the principle of the control of its aircraft by ships was at first unacceptable to Fighter Command.
By the end of this first phase of the war the essential contribution of aircraft to the defence of trade, and the extent to which they would condition all maritime operations was widely realised in the Home Fleet and in the squadrons and flotillas responsible for protecting our coastal shipping. Opinion had, indeed, moved a long way from the pre-war contention, which had been reflected in the Admiralty's war plans, that, when at sea, the fleet would, by virtue of its antiaircraft armaments and its carrier-borne fighters, be able to look after itself, and that the normal system of convoy and escort would afford adequate protection to our shipping against air attack.
While the staffs of the two services were working out the system of protecting coastal shipping, the Admiralty was doing all it could to
equip the coastal convoys and fishing trawlers with some form of anti-aircraft armament. Early experience had shown that not only was a gun--even of obsolete type and probably ineffective--of great moral value to the crews, but that the effect of its fire on aircraft making low attacks was out of all proportion to the probability of the aircraft receiving lethal damage. Unfortunately the armament stores were nearly bare even of the light machine guns preserved after the 1914-18 war, and urgent steps, such as calling in weapons from ship and shore bases which stood in less immediate need of them, could not meet the whole of this new requirement for light anti-aircraft weapons. The Admiralty, therefore, instituted a search for substitutes and many and various were the devices of that nature sent to sea. We shall meet them again in later chapters.
It was not only the shortage of anti-aircraft weapons which handicapped the defence of merchant ships against air attack. The Navy did not possess anything like the number of trained gunners needed to fight the weapons; nor could the reservists who manned the merchant ships' defensive armaments entirely fill the gap. Though the shortage of anti-aircraft gunners did not come to a head until the following year there were, by the end of 1939, clear signs that many thousands of such men would be needed for the Merchant Navy.
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