Atlantic, battle of the

Atlantic, battle of the, 1939-45. A decisive Second World War battle. Before the war British naval experts thought ‘Asdic’ countered submarines and, like the highest German authorities, considered surface warships the best means of interrupting transport to Britain. Hitler allotted priority to submarines only after the fall of France, which gave German submarines greater range from Bay of Biscay harbours. In the first half of 1941 the Germans began to win, using ‘wolf-packs’ of submarines to overwhelm convoys. In June, however, the British started to decode orders, generated by German ‘Enigma’ machines, giving U-boat assembly areas in the Atlantic. In July 1941, shipping losses from submarine attack fell to less than one-third of those in June. Early in 1942, the Germans recovered; they began to read allied convoy orders and again made their own orders indecipherable. Losses to allied ships exceeded combined British and American building. In 1943, however, at twelve times the volume of 1941, US construction far exceeded losses. ‘Very long-range’ aircraft and small escort aircraft carriers improved allied reconnaissance and attack, together with high-frequency direction finding, which enabled warships to locate U-boats as soon as they made radio signals. The allies won the battle of the Atlantic for good in summer 1943.