After the carnage of 1942 and early 1943, the Allies had seen a stunning turnaround in the Atlantic. By September 1943, most U-boats had been swept from the Atlantic waters. This was thanks not only to the new high-speed bombes but also to a host of other Allied war measures: advances in radar, sonar, and high-frequency direction finding; more aircraft carriers and long-range aircraft; better convoy systems.
