Admiral Nagano directed the actions of Japan's Navy for most of World War II. Prior to the war, he served as a delegate to a number of the significant naval conferences discussing quotas on Japan's Navy in relation to other world powers, including the United States. He was present at the 1922 Washington Naval Treaty allocating a 5-5-3 ratio, with Japan allowed the fewest battleships. During the war, he was against Admiral Yamamoto's attack on Pearl Harbor, but ultimately approved the mission. As a result of his actions during the war and approval of the Pearl Harbor attack, he was selected for trial as a Class A defendant. Nagano's American Associate Counsel was John G. Brannon. Hachiro Okuyama served as Japanese Chief Counsel with Shimao Iwai, Kunji Kanase, and Shigeo Yasuda serving as his Japanese Associate Counsel. Before the trial concluded, Nagano died in Sugamo Prison on January 5, 1947. Controversially, he was later enshrined, along with 13 other convicted defendants, at the Yasukuni Shrine.