One of The New Yorker 's " Best Books of the Year" * A Gilder Lehrman Military History Prize Finalist "Authoritative. . . . [Reynolds's] contribution to our understanding of the rise of American intelligence is unparalleled." —Journal of Intelligence History “The most thorough and detailed history available on the origins of U.S. intelligence.” —Michael Morell, former Deputy Director and Acting Director, CIA Historian and former CIA officer Nicholas Reynolds, the New York Times bestselling author of Writer, Sailor, Soldier, Spy, uncovers the definitive history of American intelligence during World War II, illuminating its key role in securing victory and its astonishing growth from practically nothing at the start of the war. The entire vast, modern American intelligence system—the amalgam of three-letter spy services of many stripes—can be traced back to the dire straits the world faced at the dawn of World War II. Prior to 1940, the United States had no organization to recruit spies and steal secrets or launch covert campaigns against enemies overseas and just a few codebreakers, isolated in windowless vaults. It was only through Winston Churchill’s determination to mobilize the US in the fight against Hitler that the first American spy service was born, built from scratch against the background of the Second World War. In Need to Know , Nicholas Reynolds explores the birth, infancy, and adolescence of modern American intelligence. In this first-ever look across the entirety of the war effort, Reynolds combines little-known history and gripping spy stories to analyze the origins of American codebreakers and spies as well as their contributions to Allied victory, revealing how they laid the foundation for the Cold War—and beyond.