1960, Duke, a personal friend of Kennedy, was asked to serve as chief of protocol for the U.S. State Department with the rank of ambassador. He held this position until 1965. As a vocal supporter of equal rights, "he resigned from the Metropolitan Club of Washington after it refused to admit black diplomats" in 1961. His most visible task during his term as chief was to supervise the protocol for world leaders who attended the funeral of John F. Kennedy on November 25, 1963. At the end of his term as chief of protocol, the Johnson administration asked him to serve as U.S. Ambassador to Spain, which he did from 1965 to 1968. He then served as Chief of Protocol a second time, for less than six months, until he was appointed to become the U.S. Ambassador to Denmark. He served in that position for seven months. In 1969, he was awarded an honorary LL.D. degree from Duke University. Following Vice President Hubert Humphrey's defeat by Richard Nixon, and with the Democratic Party again out of power, he was again out of the U.S. Foreign Service. In the early 1970s, he was appointed by Mayor Abraham Beame to serve as Commissioner of the New York City Department of Civic Affairs and Public Events with a staff of 17 until he resigned in 1976 to work for Jimmy Carter's campaign for the presidency. When Carter defeated Gerald Ford in the 1976 presidential election, the Democrats were again in power, and in 1979 the administration brought him back again to serve as the U.S. Ambassador to Morocco, a position he held until 1981, when he was succeeded by Joseph Verner Reed, Jr. following Ronald Reagan's election to president. Later years Upon his return to the United States, the National Committee on American Foreign Policy awarded him with the inaugural Hans J. Morgenthau Memorial Award "in recognition of his exemplary foreign policy contributions to the United States". From 1992 to 1995, Duke served as the elected president of the Council of American Ambassadors. He was a member of the Sons of the American Revolution. He also served as the chancellor of the Long Island University, Southampton Campus. After his death, his papers were archived by Duke University in North Carolina. Personal life In 1937, he married Priscilla Avenal St. George (1919–1995) at St. Mary's-in-Tuxedo Episcopal Church. She was the daughter of George Baker