Admiral Duncan was XO of the USS Hutchins (DD-476) in 1942 in combat action in the Aleutians and South Pacific, then CO of the USS Wilson (DD-408) taking part in action in the South and Central Pacific. After World War II, he served as XO of the USS Wisconsin (BB-64) and CO of the Chilton (APA-38), Assistant Chief of Staff for Operations CinCPac, Commander Amphibious Group One, and Commander Amphibious Training Command, Pacific Fleet. Discussions in his oral history cover various naval topics: neutrality patrol in the Atlantic, transfer of 50 destroyers to the Royal Navy, planning for CinCLant and newly established SACLant command, amphibious warfare in its early stages and later developments, naval education, and Navy Reservists. Volume II gives detailed coverage of the admiral's tours of duty as Assistant Chief of the Bureau of Naval Personnel (1962–1964) and as Chief of the Bureau (1968–1970). This position includes a notable account of the admiral's years as liaison of BuPers with Rickover and the nuclear program of the Navy. Included in the volume is coverage of several large sea commands that span a significant period in history: Atlantic Fleet Cruiser-Destroyer Force (1964–65)

Atlantic Fleet Amphibious Force (1965–67)

the Second Fleet (1967–68). In Volume III, Admiral Duncan provides a wealth of detail on his service as Chief of Naval Personnel from 1968 through 1970 and as NATO's Supreme Allied Commander Atlantic from 1970 until his retirement in 1972. In discussing both tours, he provides explanations of what the jobs entail and illustrates with examples from his own tenure. As chief of BuPers, he managed the Navy's manpower, justified programs before Congress, and dealt with budgetary considerations. Included was the requirement to reduce sharply the manpower allocations to meet budget requirements in 1969-1970. Serving as SACLant was one of three jobs the admiral held simultaneously, and he tells in this volume of the NATO billet. He worked with both high-ranking civilians and military officers in other countries, was involved in planning, and in the conduct of NATO exercises. The concluding Volume IV covers Admiral Duncan's duties in two of the three "hats" he wore from 1970 through 1972. In Volume III, he told of his NATO hat. At the same time, he had the U.S. joint-service title of Commander in Chief Atlantic and the U.S. Navy billet as Commander in Chief Atlantic Fleet. The admiral explains the differing concerns that went with each job and makes a case for having them held by two different admirals, as is done in the Pacific. As in the previous volume, he explains what the jobs entailed and illustrated through his experiences from his own service. This volume concludes with a detailed recounting of Admiral Duncan's involvement with Admiral Elmo Zumwalt, who was Chief of Naval Operations during Duncan's final years on active duty. The relationship began in BuPers when Zumwalt was a lieutenant commander, ten years junior to Duncan, and concluded when Zumwalt was Duncan's senior.