Born in Germantown, Pennsylvania, Gates was the son of Thomas S. Gates Sr., an investment banker and lawyer who was president of the University of Pennsylvania from 1930 to 1944. Gates graduated with his Bachelor of Arts in English in 1928. During World War II he served in the Navy, rose to the rank of Lieutenant Commander, and participated in campaigns in the Pacific and Mediterranean areas. He was released from active duty in October 1945. President Eisenhower appointed Gates Under Secretary of the Navy in October 1953 and Secretary on 1 April 1957, positions in which he earned the president’s approval. It was a foregone conclusion when Gates became Defense Secretary Neil McElroy’s deputy on 8 June 1959 that he would succeed him.
On January 18, 1961, Gates was presented with the Medal of Freedom by President Dwight D. Eisenhower. After he left the Pentagon, he joined Morgan and Company in New York, which eventually became the J.P. Morgan Bank. President Richard M. Nixon appointed him chairman of the Advisory Commission on an All-Volunteer Force, which presented its influential report in November 1969.In 1976-1977 he served, with the rank of ambassador, as chief of the United States Liaison Office in the People’s Republic of China. Gates served as a Trustee of the University of Pennsylvania from 1948 to 1983 until he died in Philadelphia, Pennsylvania on 25 March 1983.