Why did Britain decide in 1947 to build an atomic bomb? What plans were there for using it? Employing the previously inaccessible confidential records of the British government in the decade after World War II, including those of the Chiefs of Staff, this book provides the first detailed assessment of the technical, political, and economic factors behind British nuclear policy. The authors argue that British thinking on nuclear deterrence was distinctive and made a unique contribution to early theorizing on nuclear weapons, and compare the strategic thought of Britain and the United States.