A detailed account of the dramatic success and failures of Hitler's U-boats in the mid-war years during the best-known naval campaign of World War II.

At the start of 1942, the Germans benefited from the lack of American preparations to defend shipping along the US East Coast, and this 'Second Happy Time' saw serious Allied losses between January and July 1942. After this Allied disaster, Admiral Dönitz planned to shift his focus to the North Atlantic. This was interrupted by the Allied invasion of North Africa, which diverted the U-boat force until the end of 1942. When Dönitz was finally able to move his U-boats into the North Atlantic, they inflicted very heavy losses on Allied shipping and, by March 1943, looked poised for victory.

Respected naval historian Mark Stille analyses this critical period in the Battle of the Atlantic, describing how Allied advances in technology and intelligence saw the balance shift, with a stunning 34 boats lost in May 1943 alone and the Germans forced to withdraw. He also examines whether the Germans could have ever actually threatened the Allied sea lanes of communication effectively. Using maps, diagrams, photographs and stunning battlescene artworks, the weapons, personalities, and tactics of the opposing sides are brought vividly to life in a unique and engaging way.