For four centuries the British realm depended on sea power to defend itself against a myriad of threats. The Royal Navy established itself as the "Sovereign of the Seas," helping transform a small island nation into the center of a global empire. But Britain's maritime services faced an unprecedented challenge during World War II, and the survival of the nation was at stake.

The Longest Campaign tells the epic story of British sea power in the Second World War. It is a comprehensive and detailed account of the activities, results, and relevance of Britain's maritime effort in the Atlantic and off northwest Europe. Military historian Brian Walter looks at the entire breadth of the maritime conflict, exploring the contribution of the Royal Navy, Royal Air Force, and British merchant marines, as well as their Commonwealth equivalents.

Walter puts the maritime conflict in the context of the overall war effort and shows how the various operations and campaigns were intertwined. Finally, he provides unique analysis of the effectiveness of the British maritime effort and role it played in Allied victory.