In the year 1942 there had been some improvement in the numbers of aircraft available to the Command, and the types of aircraft that were to come into service. There had been considerable improvements in the equipment available and armament–most notably the Leigh Light and the 250 lb Torpex-filled depth charge fitted with a pistol able to detonate at 25 ft depth. The Leigh Light enabled the Command to attack U-boats at night.
By the end of 1942, most reconnaissance squadrons appear to have been equipped with Mark II ASV, and some, such as No. 500 Squadron, had Yagi aerials for homing. Although the initiative using Mark II ASV, which transmitted at 1.5m wavelength, had been lost due to U-boats gaining the use of the French Metox receiver, the U-boats had nevertheless been put on the defensive, as shown by their attempts to improve their anti-aircraft armament with machine-guns. They were also seen to be on the defensive by asking the Luftwaffe to cover them in the Bay of Biscay.
In 1942 Coastal Command claimed twenty-seven enemy submarines sunk, one captured and eighteen damaged. Some of the successes had been shared with HM ships. This year marked the entry of the United States Navy squadrons operating under Coastal Command control in Iceland, and two of the sinkings were claimed by VP73 PBYs and one of the U-boats damaged by a PBY of VP84.
More operations were being undertaken by longer-range aircraft, including the Liberator, Flying Fortress and Catalina. Nonetheless, the successes of medium-range aircraft such as the Hudson operating from both Iceland and Gibraltar still served a useful purpose in antisubmarine warfare.
There was still a need for greater numbers of the long-range Liberator bases, provided with longer runways able to accept the heavier four-engined aircraft; a need also for aircraft to be equipped with Mark III radar, and for the provision of radio altimeters and a low-level bombsight. Owing to campaigns in the Middle East and the Far East, a number of squadrons had been taken from Coastal Command for those overseas postings.
1943 POLITICAL DECISIONS
The Allied leaders arranged a number of conferences in 1943, and all had a direct or indirect bearing on Coastal Command. Those relevant to Coastal Command’s antisubmarine operations took place in Casablanca in January and at Washington in March. At the Casablanca conference in January, the Combined Chiefs of Staff decided that the first charge on the combined Allied resources in 1943 should be directed towards the defeat of U-boats.
For the Air Officer Commander-in-Chief of Coastal Command at that time, Air Chief Marshal Sir Philip Joubert, ‘It revealed the degree of concern with which the Battle of the Atlantic was regarded, and it held promise, if interpreted literally, of Coastal Command receiving its full requirements.’82 At that time, as throughout his tenure with the Command, Sir Philip appreciated that fully to satisfy the requirements of Coastal Command, it would be at the expense of the resources for other forces.83 Prior to the Washington Conference there had been no coordination of the Canadian (RCN and RCAF) forces, and likewise no coordination between the American Navy and Air Force.
The RCN and RCAF had needed to settle their differences in much the same way as had prevailed with Coastal Command and the Admiralty. They were resolved with maritime air sorties being under the operational direction of the naval commander responsible for protecting shipping, but the Air Officer Commanding was to exercise general operational control.
This agreement was considered necessary to satisfy the American Admiral King (Cominch). Portal, the CAS, appeared more interested in bombing Germany, his ‘Course B’ for winning the war.
There had been five separate controls for the Americans’ naval and air forces on their eastern seaboard, but following the conference chaired by Admiral King, a statement was issued on 11 March that:
All ASW aviation of the Associated Powers based in this region is to be under the general operational control of the Canadian AOC EAC Halifax who, under general operational direction of the C-in-C North Western Atlantic shall be responsible for the air coverage of all shipping within range, including Greenland convoys and other shipping under US control.
Decisions made at a conference at Washington in March had an immediate bearing on the Battle of the Atlantic. That was to close the 700-mile ‘Mid-Atlantic Gap’ by having convoys with escort carriers, which were provided by the United States Navy.
A further outcome of the conference in March was the reorganisation of the convoy system on the eastern seaboard of the Americas, with both the United States Navy and the RCAF having anti-submarine forces that included VLR (very-long-range) aircraft in Newfoundland. For the effective protection of the North Atlantic convoys it was necessary to have intelligence of U-boat movements, and this was gained largely through decoding of the enemy’s signals.
The British Admiralty began the organisation by issuing a daily message prefixed ‘Stipple’, and categorised convoys according to whether they were under attack or threatened, needing air cover in the near future, or considered out of danger. Account was taken also of the fast liners such as the Queen Elizabeth that sailed independently. Coastal Command prefixed its messages ‘Tubular’, which outlined the probable U-boat areas with the object of helping to coordinate air patrols under Eastern Air Command at Halifax and those under No. 15 Group at Liverpool.
In applying this procedure, Air Marshal Slessor adopted the view that it was for the Admiralty to state what air cover was required, but for the Air Officers to decide how they could best deploy their air forces to achieve the required aim. He advised the Canadians that it could be through day-to-day discussions rather than to ‘raise it as a policy issue’.
The practical application of the agreement made at the Washington Conference was that there was daily telephoning between the Admiralty, Coastal Command HQ, and ACHQ Liverpool to check the dispositions of convoys and of the believed positions of U-boats, which were based largely on decoded German signals. All of Coastal Command’s Groups and HQ at Iceland, Gibraltar and the Azores, plus the RCAF at St John’s and Cominch in Washington, signalled each other as to what they were able to undertake the following day. Britain and Canada were to become entirely responsible for convoys on the North Atlantic route, with their headquarters at Liverpool, England, and Halifax, Nova Scotia, respectively. It was to result in a shuttle service of VLR Liberators between Newfoundland and Iceland that thus covered the gap south of Greenland.
The crucial aspect that resulted from the Allies’ agreement was that VLR aircraft were operated from Newfoundland in protecting the North Atlantic convoys, notably those from Halifax. The VLR aircraft that sortied from Newfoundland were in addition to Coastal’s limited VLR Liberators operating from Iceland. This resulted in a shuttle service of Liberators in sorties of about 12–13 hours’ duration between Newfoundland and Iceland. Thus was the notorious Mid-Atlantic Gap closed. That the United States agreed to provide VLR aircraft to operate from Newfoundland, for a total of thirty-six VLR aircraft to operate from there, and to accelerate the supply VLR Liberators for the RCAF in that area, represented a considerable concession on the part of Admiral King, whose thoughts were always directed to the Pacific rather than the North Atlantic. Sir John Slessor considered this to have ‘more than any other single factor … closed the Mid-Atlantic Gap’.
Both Sir Philip Joubert and Air Marshal Slessor had wished for the Atlantic battle to be considered in its entirety by the Allies, and that aim had now been achieved.90 Any dissension, notably from Admiral King, had effectively been removed. Appropriately, after Churchill attended a conference at Quebec in August, HMS Renown, in which he returned, was escorted by No. 10 Squadron RCAF Liberators operating from Gander.
A decision had been made at the Casablanca conference in January to invade Sicily. This may have had no immediate effect on Coastal Command’s anti-submarine operations over the Atlantic, but resulted in some of the Command’s squadrons, such as Nos 500 and 608, remaining in the Middle East, which might otherwise have been deployed in the Battle of the Atlantic.
By February 1943 there were a series of changes of command. Admiral Horton had been appointed C-in-C Western Approaches at Liverpool, Admiral Dönitz had succeeded Admiral Raeder as Commander-in-Chief of the Kriegsmarine, and Air Marshal John Slessor became AOC-in-C of Coastal Command. For Dönitz it meant that he was able to approach Hitler direct and plead more strongly for his requirements in his U-boat campaign, including not only materials for U-boats but his requirement for support from the Luftwaffe.
Admiral Horton at ACHQ Liverpool was an ex-submariner and therefore, in fighting the Battle of the Atlantic, was well suited to the task and able to anticipate how the enemy would react to any of his decisions. As Dönitz stated:
Under the command of Admiral Horton the British anti-submarine forces made great improvements … particularly in tactical leadership and morale. Admiral Horton was better qualified than anyone else to read the mind of German U-boat Command and therefore to take steps which would render more difficult the prosecution of our U-boat campaign.
For Coastal Command, it was apparent that the views of its naval liaison officer, Captain Peyton-Ward, also an ex-submariner, were considered by Admiral Horton in respect of his proposals in connection with the U-boat war.
Air Marshal Slessor had the advantage of having attended the Casablanca Conference, and earlier in his service he had visited America as the representative of the CAS and met the American Chiefs of Staff. Therefore, he was effectively well briefed to understand the American points of view when liaison was necessary in combating U-boats and requiring supplies of American-built aircraft and equipment.
At the Washington Conference in May, Winston Churchill recorded that he ‘did not propose to deal with the U-boat war’; rather was he concerned with the invasion of Sicily and to ‘take the weight off Russia’. That Churchill was prepared not to deal with the U-boat war at that time was understandable, as Sir John Slessor stated: ‘The Gap was closed in May’, and Dönitz withdrew U-boats from the North Atlantic on 24 May.
As late as May 1943 Mark II ASV was still being used in operations, although by then Germany had the Metox receivers to detect the 1.5m radiations. A modification undertaken on at least one squadron was to install a variable condenser in the output circuit, to act as an attenuator and thus reduce the strength of the signal after a U-boat had been located, to give the enemy the impression that the aircraft was disappearing.
Aircraft of some units, such as No. 500 Squadron, were equipped with Yagi aerials for their Mark IIs, which should have enabled them to home onto a target with greater accuracy and to obtain a much stronger return signal.
There was a radical change in 1943 with radar equipment when the Mark III was becoming available to Coastal Command. Its most important advantage was that it transmitted on a much shorter wavelength of 9.1 cm instead of 1.5m as with the Marks I and II, and could not be detected by the Metox receivers in U-boats.
Instead of fixed aerials there was a rotary scanner, and thus the return signals gave a visual trace through 360 degrees on a CRT known as the Position Plan Indicator (PPI). This was in contrast to the Mark II, which (unless beam aerials were installed) would cover only a forward arc. Near land, it would give a trace of the outline of the coast while vessels on the surface of the sea would be indicated by little more than dots on the screen. Mark III radar had another important advantage over the earlier marks, which was the lack of ‘sea returns’ that masked targets at short range. Some operators found that targets remained visible on the screen down to a quarter of a mile. Other forms of radar were being developed for Bomber Command, such as ‘Oboe’, ‘H2S’, and ‘GEE’; there was thus a conflict of interest for components such as magnetrons and CRTs that were common to the various forms of radar. Production of radar was being undertaken in both North America and the United Kingdom, and this was one occasion when priority was given to Coastal Command, with the supply of a limited number of Mark III ASV.
There was obvious cooperation between Britain and USA in respect of radar in development, production and availability; it was such that, ‘As a stop gap, fourteen 10 cm [9.1 cm] sets were built at the MIT [Massachusetts Institute of Technology] radiation laboratory and flown to the British, to be used in the RAF planes patrolling the Bay of Biscay.’ The VCAS had also decided in favour of Coastal receiving 9.1 cm radar; in preference to Bomber Command being supplied with H2S radar that would have needed related components, and provision had been made at a Cabinet Anti-Submarine Committee meeting for the two Wellington Leigh-Light squadrons, Nos 172 and 179, to be equipped with the new radar by February 1943.
That the earlier marks of ASV could be detected by U-boats was in one respect a disadvantage to the enemy. If Coastal Command deployed enough aircraft in a transit area such as the Bay of Biscay, it could be ‘swamped’ with 1.5m transmissions. The U-boats would then have the option of either submerging or risking being attacked by remaining on the surface.
A series of alarms would at the very least affect the morale of the U-boats’ crews by their being made aware of hostile aircraft. There would also be a limit to the number of crash dives that could be undertaken, due to reducing supplies of compressed air. The U-boats, nevertheless, were able to detect Mark II ASV signals at 30 miles, while Coastal aircraft with Mark II ASV would detect U-boats at about 6½ miles, and perhaps up to 10 miles.
The German reaction was that Admiral Dönitz had ordered his U-boats to dive for thirty minutes when they became aware of radar transmissions from aircraft, but he stated that it was of ‘doubtful effect’. Sir Philip Joubert deployed his aircraft accordingly by so arranging patrols in the Bay of Biscay transit area in what was part of Operation ‘Gondola’ during late January and early February. The patrols extended from the inner Bay at about 3ºW using the shorter-range aircraft, and to as far as 22ºW with his limited number of Liberators during the day and Catalinas with Leigh Lights during the night. Sunderlands, Halifaxes and Wellingtons covered an area 120 miles east of 10ºW, and Leigh-Light Wellingtons that same area during the night.
Sir Philip was conscious of having a very limited number of Leigh-Light Wellingtons equipped with Mark III radar, and limited also in the numbers of Liberators available. Throughout his tenure as Commander-in-Chief of Coastal Command, it was to be as he said, ‘Make do and Mend’.105 He had concentrated his forces in the Bay of Biscay because in that area he could take the initiative. In contrast, in the area of the Atlantic convoys, the enemy had the initiative. By deploying his forces in the Bay of Biscay rather than the Atlantic, his shorter-range aircraft, such as Wellingtons, could play a more active part and for a greater length of time. Furthermore, there was a greater likelihood of obtaining sightings of U-boats as they were in a more confined area.
Joubert would have been well aware of the risks for aircrew in flying to about 3ºW, well in range of enemy aircraft, but as operational records of both Sunderlands and Wellingtons were to show, their crews could give a good account of themselves, and they were prepared to accept the risks.
ARMAMENT AND TACTICS
Following the unsuccessful tactics of U-boats being ordered to dive for thirty minutes on becoming aware of aircraft using radar, further measures were attempted. They included increasing the armament of U-boats, with the addition of machine-guns, quadruple installations of 2 cm cannon, and a 3.7 cm cannon. Additionally, some U-boats were given exceptionally heavy anti-aircraft armament, with the intended object of attracting aircraft to shoot them down. The additional armament did, however, make the vessels top heavy. These measures were to prove successful only briefly, due to the surprise advantage and, it appears, against some inexperienced pilots.
Thereafter, U-boats found that aircraft would circle and call for assistance. As was to be acknowledged by the enemy in the Bay, ‘It was patrolled by units of Nos 15 and 19 Groups … which were highly trained in antisubmarine methods.’ It was so. As one aircraft captain, Flt Lt Baveystock, after getting a blip on his radar at 9 miles stated, ‘We felt sure it was our quarry as the size of the blip was the same as we normally got from our tame sub [a Royal Navy submarine that was cooperating with Coastal Command training].’ After dropping a flame float to mark the position of the U-boat that had crash-dived, Baveystock started baiting tactics to give the impression of having left the area. He added, ‘… knowing that the U-boat would have to resurface to recharge’. Baveystock correctly estimated when the U-boat would surface; and despite its improved anti-aircraft armament of quadruple cannon, it was sunk.
Because of Coastal Command’s ability to detect U-boats on the surface, and following the improved anti-aircraft armament on U-boats, Dönitz ordered some to traverse the Bay of Biscay in convoys of up to five in number, remaining on the surface and being prepared to ‘fight it out’ against Coastal Command’s aircraft.
The first outward-bound group of U-boats sailed on 12 June 1943.
The failure of traversing the Bay by U-boats on the surface was clearly demonstrated by three U-boats, U-461, U-462 and U-504, although in fact they were only on the surface for one of the three to charge its batteries. Because they were in convoy, all had to be on the surface. The senior officer, Captain Wolf Stiebler, recalled: ‘It wasn’t long before several planes were above us … our defence with the quadruple guns worked very well.…’ But when two aircraft attacked from different angles the quadruple cannon could counter only one, leaving the other aircraft free to attack.
One of the aircraft captains, Flt Lt Dudley Marrows, recalled: ‘When we got within attack range aircraft were circling, the U-boats manoeuvring in formation keeping bows on to aircraft, and putting up a formidable barrage of cannon and machine-gun fire.’ Marrows found, as did other aircraft captains, that U-boats could always outmanoeuvre aircraft. Nevertheless, in his attack with Sunderland U/461, he sank U-461. Against orders he dropped his own dinghy, which saved Captain Stiebler and some of his crew.
This episode on 30 July 1943 appears unique in Coastal Command’s records, as all three U-boats were sunk, with the support of an escort group of sloops, which in turn was operating with the cooperation of a Catalina aircraft. This cooperation between the Navy and the Command had been long advocated; it was delayed, however, due to the lack of escort vessels in the Navy. In addition to such as Marrow’s Sunderland, and the Catalina, there were other aircraft types, including a Liberator and Halifax, which was indicative of an improvement in Coastal Command’s supply of aircraft, but the question of types of aircraft with the appropriate equipment was still not completely resolved.
In May and June 1943 another weapon was being used against U-boats. It was the rocket projectile, and for the RAF its first successes were gained by Hudsons of Nos 48 and 608 Squadrons in the Mediterranean. Its success as an anti-submarine weapon was confirmed by the sinkings of U-755 and U-594.
Although rocket projectiles could be used with success against U-boats, there was perhaps more to be said for them to form part of the armament together with cannon of long-range fighters such as Beaufighters, which came to constitute the strike wings of Coastal Command: particularly so, as Beaufighters were more strongly built and better able to withstand the stresses involved.