Pate was a veteran of World War II, seeing action at Guadalcanal and Iwo Jima, and later served in Korea, and pre-war expeditionary service in Santo Domingo and China.

After a brief tour of enlisted service with the United States Army in 1918, he entered the Virginia Military Institute, graduating in June 1921, with a Bachelor of Arts degree.

In the spring of 1939, he became assistant chief of staff for supply, 1st Marine Division, at New River (later Camp Lejeune), North Carolina, and while there was promoted to lieutenant colonel in January 1942.

Serving in that capacity from September 11, 1944, to November 1, 1945, Pate, then a colonel, was cited in particular for his performance of duty during amphibious operations on Palau, Iwo Jima and Okinawa.

The award was for exceptionally meritorious service at Guadalcanal as assistant chief of staff for supply of the 1st Marine Division during the United States' first offensive against Japan.

In July 1954, Pate was appointed assistant commandant of the Marine Corps and chief of staff, serving in that capacity with the rank of lieutenant general for eighteen months.

Aware of the necessity for maintaining combat readiness throughout the post armistice period, he implemented an aggressive, realistic and comprehensive training program of dual purpose consisting of orientation and indoctrination in the battle techniques of both ground warfare and amphibious assault operations.