Feeding the Nation - The Battle of the Atlantic

As war broke out on 3rd September 1939 Britain was importing more than a million tons a day of food, petrol and other vital supplies. It was realised that Germany would target merchant shipping in an attempt to starve the country into submission. To provide as much protection as possible a convoy system was introduced immediately, although very fast and very slow ships could sail alone. The subsequent Battle of the Atlantic, covering millions of square miles of sea, did not end until the last day of the war.

The first phase lasted until the fall of France in June 1940. Initially Germany had only about 50 submarines (U-Boats), not all operational, and mostly small, and so their ability to detect and damage convoys was very limited. Once France fell Germany acquired bases on the Atlantic coast much nearer to the shipping routes while Britain lost the support of the French Navy and it’s strength was depleted by losses during the Norway campaign and at Dunkirk. Germany was rapidly building bigger, better equipped, longer ranged U-Boats and these, operating in “wolf packs”, together with surface ships and aircraft, were able to inflict huge damage on the poorly escorted convoys. Forced to avoid the Mediterranean Sea and the Suez Canal. British shipping had to take the much longer route round the Cape of Good Hope, effectively halving the capacity. However, it was enough - Britain was not forced to surrender.

The situation began to improve from mid 1941. Under the “Forces for Bases” agreement signed 2nd September 1940 the USA gave Britain fifty old World War One destroyers which, after refitting, proved invaluable. A Lend-Lease agreement was then signed on 11th March 1941, giving the USA the ability to supply almost anything to support the British cause. With improved technology and tactics new warships were more effective in tracing and attacking U-Boats. By June 1941 the code breakers at Bletchley Park could read the instructions sent to U-Boats and the communications between them giving the escorts valuable information on their whereabouts. Losses, though still substantial, were greatly reduced.

However, the entry of the USA into the war in December 1941 opened a vast new area of American waters to U-Boat attack. The USA did not introduce escorted merchant convoys until May 1942 partly due to other priorities such as the war in the Pacific and the need to escort troop ships to the UK and military supplies to Russia. On 1st February 1942 Bletchley Park suddenly lost the ability to decode German naval communications following the introduction of a new Enigma machine and with it a far more complex code. The new codes were not broken until March 1943. In December 1942 it was realised that German code breakers could read the British naval cypher number 3, and had probably been doing so since March 1942. The result of all this was again huge losses throughout 1942 and into early 1943. The climax to the battle came in March 1943 when, world wide, 120 ships were sunk including 82 in the Atlantic while only 12 U-Boats were destroyed. However, with Bletchley Park again reading the German codes the tide of battle turned again. In May 1943 34 U-Boats (25% of the operational strength) were destroyed in the Atlantic for the loss of 34 merchant ships. Germany never regained the initiative, and by the end of June the Battle of the Atlantic was effectively over.

Over the course of the Battle Britain and its Allies lost around 3,500 merchant ships and 175 warships. Germany lost 783 U-Boats and 47 surface ships including 3 battleships.