He graduated from Western High School, Washington, D.C., in 1937, and from the United States Military Academy at West Point in 1942.

He then entered flight training and received his pilot wings at Lubbock Field, Texas, in December 1942.

He next attended B-26 Marauder transition school at Fort Worth and Del Rio, Texas, where he later became an instructor.

He went to Ramey Air Force Base, Puerto Rico, in July 1956, where he served as deputy commander of the 72d Bombardment Wing.

His first assignment was as a member of the Joint War Games Control Group, and later he served as deputy director for operations.

Clay's military decorations and awards include: the Air Force Distinguished Service Medal with four oak leaf clusters; Legion of Merit; Distinguished Flying Cross; Bronze Star Medal; Air Medal with 10 oak leaf clusters; Joint Service Commendation Medal with oak leaf cluster; Army Commendation Medal; Purple Heart; Croix de Guerre with Étoile de vermeil (France) with Gold Star; National Order of Vietnam, Third Class; Republic of Vietnam Air Force Distinguished Service Order, First Class; Korea National Security Medal; and Republic of Vietnam Cross of Gallantry.