Thomas Gates was secretary of defense under President Eisenhower from December 2, 1959, to January 20, 1961. He graduated from the University of Pennsylvania, where his father later became president, and joined his father's investment firm, Drexel and Company, as an associate. He later became a partner in the company.

Gates joined the U.S. Naval Reserve in 1935 and was called up in April 1942 and sent to Quonset Point Air Intelligence School before being assigned to staff of CINCLANT, the Commander-in-Chief of the Atlantic Theater. While aboard the aircraft carrier USS Ranger, Gates was involved in the landings of American troops at Casablanca. In 1943, while serving on the aircraft carrier USS Monterey in the Pacific, he participated in the landings at Tarawa and Kwajalein Island, and from 1944 to 1945, he assisted in Operation Dragoon, a planned Allied invasion of France.

He was discharged in October 1945 with the rank of commander and, in 1946, began work as director of Beaver Coal Corporation, becoming its vice president in 1948. On October 2, 1953, Gates returned to national service as undersecretary of the Navy (1953-1957), secretary of the Navy (1957-1959), and assistant secretary of defense (1959) before becoming the new secretary. For a time, President-elect Kennedy considered him as a possible secretary of defense.

Gates would become president and director of Morgan Guaranty Trust upon his retirement from government in 1961. In 1976, President Ford, with whom he had served in the Navy, appointed him U.S. Liaison to China, with the rank of ambassador. Gates retired from the position in 1977 and died in 1983. His legacy lives on in the form of a naval cruiser, the USS Thomas Gates.