A significant factor in defeating U-boats was the formation of hunter-killer groups, consisting of multiple destroyers, corvettes, and frigates working together to search for and destroy submarines. By using sonar, radar, and depth charges, these groups became increasingly effective in detecting and eliminating U-boats in convoy attacks.
Ultra decryption
Ultra was the code name for British signals intelligence during World War II. The Ultra program cracked the German Enigma coding machine (used to send enciphered messages between U-boats and headquarters). Access to German communications allowed them to anticipate U-boat movements and redirect convoys accordingly.
Long-range aircraft.
The development of longer-range Allied aircraft like the Consolidated B-24 Liberator, Lockheed Ventura, and Avro Lancaster became potent adversaries for U-boats in the mid-Atlantic and western approaches.
Naval radar
Radar technology provided ships and aircraft with improved detection capabilities beyond visible ranges, making tracking and targeting U-boats in both surfaced and submerged conditions more accessible. This was especially effective during night-time battles when U-boats had historically excelled
Advances in anti-submarine warfare:
During the latter stages of WWII, improved sonar devices aided in the precise detection of underwater enemy submarines. Additionally, depth charge designs were refined for better detonation upon contact.
Other key factors included the mass production of anti-submarine vessels for patrol duty and escorts and the invention of acoustic torpedoes used by both ships and aircraft against submarines submerged at greater depths.
Although they had inflicted substantial military setbacks and tremendous psychological fear. In May 1945, Admiral Karl Dönitz surrendered all surviving U-boats, as they could no longer effectively counter advances in military strategy, technology, and Allied resources.