Japanese troops advancing near Mandalay, Burma, in May 1942. Photo: adoc-photos/Getty Images On May 3, 1946, at the former Army Ministry in central Tokyo, 11 international judges gathered for an extraordinary legal proceeding. The building’s auditorium had been refashioned into a courtroom, klieg lights and cables for broadcasters installed. As the judges donned their robes, they learned that 26 inmates—former military and civilian leaders of wartime Japan—had arrived from Sugamo Prison. “The International Military Tribunal for the Far East is in session and is ready to hear any matter brought before it,” the court’s marshal announced, and with that the...