Click for larger image

The Battle of the Atlantic came to a climax between March and May 1943. In the three winter months from December 1942 to February 1943, bad weather and evasive routeing of convoys ensured that losses were comparatively fewer than in the previous autumn, though sinkings in the North Atlantic still reached 119 ships (723,451 tons). However, from the end of February onwards, fortified by a U-boat operational strength nearing its zenith and a break down in Allied Ultra intelligence during the first three weeks of March, German submarines again began to enjoy great success in the mid-Atlantic gap where Allied air cover still did not reach.

Over the next twenty days, the wolf packs, which now had a strength of one hundred in the North and Central Atlantic, wrought such havoc that Allied losses again began to reach the devastating levels of 1942. One of the biggest engagements of the war took place between 16-20 March when twenty U-boats attacked two eastbound convoys totalling 100 ships. At the cost of only one U- boat, the Germans sank 21 ships, with a combined 141,000 tonnage. The overall figure for March in the North Atlantic was 476,349 tons, about 75% of the world total, with 82 of the 108 ships lost in this theatre. Most serious of all was that nearly two-thirds of these losses had been sunk while sailing in convoy. The Admiralty considered that this was the closest the Germans ever came to breaking the transatlantic lifeline between Britain and America.

However, this possibility was only a fleeting one as, over the next two months, the German offensive faltered rapidly. The foundation of the change in fortunes had been laid in January when the British and US leaders conferred at the Casablanca Conference. Churchill and Roosevelt decided that the defeat of the U-boat must become the Allies' top priority. The liberation of Europe would never be able to go ahead until the Battle of the Atlantic had been won. From 1st-12th March, British, American and Canadian naval and air force representatives at the Atlantic Convoy Conference in Washington decided upon several initiatives. Twenty Very Long Range (VLR) Liberator aircraft were to be supplied to the Royal Canadian Air Force in Newfoundland to begin the closing of the mid-Atlantic air gap. Escort carrier groups were to be introduced to provide further protection for convoys. New convoy cycles were to be created and the High Frequency Direction Finding ('Huff-Duff') network was to be increased.

Only 20 VLR Liberators were operational by the end of March but by the middle of April the number had doubled to 41. By the same time, RAF Coastal Command had 28 anti-submarine squadrons, with aircraft types including Leigh Light Wellingtons and ordinary Liberators. The number of escort vessels was increasing sharply, which often allowed convoys to be given an outer as well as an inner protective cordon. At the end of March, five support groups were established to reinforce escorts of threatened convoys and hunt for U-boats. Some had escort carriers which were able to provide convoys with their own covering airpower. Centrimetric radar, with its effective 360 degree surveillance, became operational in February. Improving weather in April made radar and 'Huff Duff 'more effective. The availability again of Ultra intelligence from the third week of March enabled these new weapons to be deployed to their maximum effect.

Losses in April were significantly lower than those of the previous month. North Atlantic sinkings fell by over 50% to 235,478 tons (39 ships). At the beginning of May, Dönitz still had approximately sixty U-boats preying on the (narrowing) mid-Atlantic air gap. Half of these were concentrated across the path of a slow eastward convoy, with another eleven waiting further ahead. For a week from 29 April during very stormy weather the U-boats engaged in a fierce running battle with the convoy and its escorts. They succeeded in sinking twelve merchantmen, but at the cost of seven of their own. During the rest of May, the wolf packs made a series of repeated, but ultimately failed, attacks. The number of sinkings was greatly reduced and some convoys crossed the Atlantic without any losses at all. Conversely, U-boat casualties were heavy. Between mid-April and the end of May, 27 were lost in the North Atlantic and nearly 100 had been sunk in the Atlantic since the start of the year. VLR Liberators had finally closed the air gap. Sea and air escorts with the convoys were now present in sufficient numbers to thwart the U-boat. At the end of May, Dönitz withdrew his battered force from the Atlantic, a clear signal that the Allies had won a decisive victory.

top