This book is the first major study of Winston Churchill's record as a naval strategist and his impact as the most prominent guardian of Britain's sea power in the modern era. The book debunks many popular and well-entrenched myths surrounding controversial episodes in both World Wars, including the Dardanelles disaster, the Norwegian Campaign, the Battle of the Atlantic, and the devastating loss of the Prince of Wales and Repulse in 1941. It shows that many common criticisms of Churchill have been exaggerated, but also that some of his mistakes have been largely overlooked. The book also examines Churchill's evolution as a maritime strategist over the course of his career, and documents his critical part in managing Britain's naval decline during the first half of the twentieth century. Churchill's genuine affection for the Royal Navy has often distracted attention from the fact that his views on sea power were pragmatic and unsentimental. For, as Christopher M. Bell shows, in a period dominated by declining resources, global threats, and rapid technological change, it was increasingly air rather than sea power that Churchill looked to as the foundation of Britain's security.