22. The code breakers were blinded again in early 1943
In early 1943, the number of U-boats operating in the Atlantic again threatened to overwhelm the convoy escorts, in part because the Germans made changes to TRITON. For over a week, the British codebreakers at Bletchley Park had no information about Doenitz’s plans. In March, 1943, over 475,000 tons of Allied shipping went down in the Atlantic, in 82 ships. In the Indian Ocean, the Caribbean, and the Pacific, another 38 ships were lost to U-boats. The Allies destroyed 12 German submarines in return.
The following month the tide turned against the Germans. U-boat losses mounted. Through April the Germans sank 39 Allied ships, totaling 235,000 tons. But many more ships got through, resupplying the nearly desperate British. 15 U-boats were lost as the Allies refined their tactics using newly developed weapons. The American shipbuilding program produced more and more destroyer escorts and destroyers, as well as long-range bombers and flying boats. Escort carriers surrounded by a task force developed specifically for anti-submarine warfare actively hunted the Germans.
