The accepted interpretation of Britain's wartime role as an island sea power is challenged by Correlli Barnett's brilliant demonstration that the dependence on seashore imports of food and raw materials, together with the obligations of Empire, were less a form of strength to Britain than a weakness. Topics discussed in this book range from strategic debates in London and Washington to gripping descriptions of the Royal Navy in action: the remorseless struggle against the U-boat in the Atlantic, the desperate convoy battles in the Mediterranean and the Arctic, and the battles in the Far East. It weaves in the rivalry between Allied and German technology an the all-important secret war of the cryptographers. This outstanding military historian has turned to maritime war and written an authoritative, meticulously researched and stirring account of the Royal Navy's part in World War II. His analysis shows clearly how vital it was for the war at sea to be won before land and air campaigns could bring final victory.