Mawdsley presents a scrupulous and magisterial account of naval warfare from 1939 to 1945. Sea power could not win World War II on its own, but the Allies were able to win it on land only by gaining command of the sea. Mawdsley manages to cover a lot of ground, examining the navies of all the belligerents without letting the narrative flag. He develops his judgments of key operations with care and clarity. Without detracting from the bravery of the Royal Air Force fighter pilots who fought against the Luftwaffe in the Battle of Britain, he shows that it was British naval superiority that forced Hitler to abandon plans to invade the United Kingdom. The famous code breakers of Bletchley Park have long received credit for winning the battle of the Atlantic, but Mawdsley points to the various technical and tactical advances in anti-submarine warfare that helped Allied convoys cross the sea. His analysis of the role of carrier-based fighter-bombers in the Pacific and the U.S. victory at the Battle of Midway in 1942—from which the Japanese never fully recovered—is more familiar but still well done.