Hitler’s U-boats posed a severe threat to Britain during the Second World War, endangering both its survival and the possibility of defeating Germany. Britain needed over a million tons of imports weekly to support the war effort, but Allied shipping losses were devastating. In June 1940, enemy submarines sank 284,113 tons of Allied shipping, a number that rose to 352,407 tons by October, while the Kriegsmarine lost only eight U-boats during the same period. Losses peaked in mid-1942, with 124 ships sunk in June, yet German U-boat casualties remained minimal. Replacement ships could not keep up with the mounting losses, and the Allies’ position grew increasingly precarious.

The struggle against U-boats became a monumental effort. Jak P. Mallmann Showell’s book examines this battle in detail, focusing on Allied tactics, technologies, and innovations. Key strategies included radar, Enigma codebreaking, and the convoy system to combat German “wolfpacks.” Allied aircraft successfully drove U-boats from the British coast, while advances in sonar and weaponry, such as sonic torpedoes and rockets, gradually turned the tide of the battle.