Christopher Bell acknowledges at the beginning of Churchill and Sea Power that any historian writing on Winston Churchill must necessarily justify a project that adds to a crowded field. In the course of his book, Bell provides this justification with a fresh approach: taking the long view of Churchill's strategic thought about British sea power over his whole career, rather than simply in key episodes or in times of war. The attention to Churchill is grounded in Bell's larger interest in the highest levels of sea power—that is, in the civilian decision makers who allocated or withheld resources and who made strategic decisions about the navy's uses in both war and peace. Churchill was one of these decision makers in the first half of the twentieth century, influential whether he was serving as First Lord of the Admiralty (as he did twice), working as chancellor of the exchequer, or out of office entirely. Bell aims to avoid the “hero or villain” dichotomy into which much of the historical writing on Churchill often falls and tries instead to provide a balanced and complex view of a statesman whose ideas about Britain's maritime strategy and sea power were “constantly evolving” and never rigid (ix).

The book begins with Churchill's apprenticeship in the years before World War I, during which time he was appointed First Lord of the Admiralty (in 1911) and managed the building and deploying of dreadnoughts in light of Germany's new naval construction. The story then continues chronologically, with each chapter focusing on Churchill's relationship with the navy and his thoughts on British sea power in a key period of his career, from World War I through his time at the Treasury in the 1920s, to the fight against Germany, Italy, and Japan in World War II, and finally to his management of declining British naval power in the 1950s. Bell loads these chapters with well-documented details but keep the narrative interesting throughout. He also confronts historical controversies about Churchill's naval strategy as he goes, taking on the Dardanelles campaign of World War I, Churchill's naval cost cutting when at the Treasury, the unsuccessful Norwegian campaign against Nazi Germany, and the loss of the Prince of Wales and Repulse to the Japanese navy in World War II, among others.

With meticulous research into archival and other primary sources, Bell debunks many myths about Churchill's abilities as a naval strategist. He argues persuasively that many criticisms of Churchill's role in various events, which paint him as interfering, reckless, and incompetent, are based too uncritically on meager evidence or on the repetition of biased arguments from key early sources, including Captain Stephen Roskill's official naval history of World War II in the 1950s. Bell does some of his best service in correcting an assumption shared by both Churchill's proponents and his detractors: that Churchill was the center of all decisions and events. Instead, he provides evidence that, while Churchill was influential, he was always surrounded by others who participated in policy making, whether cabinet members or admirals, and that those others did not always simply do what he wanted. Churchill deserves neither all of the credit for successes nor all of the blame for failures.

Churchill emerges from Bell's careful analysis mostly vindicated as a naval strategist. He supported a limited naval campaign in the Dardanelles but opposed the landing of ground troops, which was pushed by other cabinet members. He cut spending on the navy while chancellor in the 1920s, but he argued for a defensive stance against Japan and good relations with the United States to provide security at lower cost. He had a clear idea of British objectives and use of forces in the Norway campaign, and its failures resulted from dispersal of resources ordered by other members of the War Cabinet. Finally, the blame Churchill often receives for dispatching an insufficient squadron to the Pacific, resulting in the loss of two capital ships to Japan in 1941, is misplaced, according to Bell. Churchill deployed the squadron as a political deterrent and a prod to the United States; he never assumed such a small force would be sufficient for war. Along with these vindications, however, Bell does take care to note an often-overlooked strategic mistake Churchill made: despite what he later claimed in his own books, Churchill did not give enough attention to the antisubmarine campaign in World War II. Instead, he diverted too many resources to strategic bombing against Germany, only belatedly focusing on the Battle of the Atlantic.

Interestingly, Bell's important study leaves the reader with a sense not just of Churchill's prowess as a naval strategist but of his wisdom as a grand strategist. In taking the long view of Churchill's career, Bell puts Churchill's views on sea power, whether operational or strategic, into a larger context. He had innovative ideas about the navy throughout his career, but he was practical and never supported the navy uncritically. In fact, much of the book shows Churchill deciding that the navy, while still necessary, had no more than a secondary role to play as air power and, finally, nuclear weapons were developed. His real abilities—as shown by many of Bell's examples—lay in seeing the big picture of Britain's national defense strategy. In the many positions he held, Churchill evaluated what the nation needed for its national security in a world of rapid geopolitical and technological changes, and he accepted that those needs went far beyond sea power.