In Reagan and Gorbachev, Jack F. Matlock, Jr., gives an eyewitness account of how the Cold War ended, with humankind declared the winner. As Reagan’s principal adviser on Soviet and European affairs, and later as the U.S. ambassador to the U.S.S.R., Matlock lived history: He was the point person for Reagan’s evolving policy of conciliation toward the Soviet Union. Working from his own papers, recent interviews with major figures, and archival sources both here and abroad, Matlock offers an insider’s perspective on a diplomatic campaign far more sophisticated than previously thought, led by two men of surpassing vision. Matlock...