During World War II, he served as member of the Army Air Forces in both the Mediterranean and Pacific theaters of operation.

His father, Colonel Edward J. Timberlake, U.S. Army, USMA Class of 1893, played for West Point in the first Army-Navy football game in 1890.

The second youngest, J. Coleman Timberlake, died in 1938 at age 32, but Patrick and his three brothers carried on the family's military tradition in notable style.

In September 1925 he entered Primary Flying School at Brooks Field, Texas, a move that would completely change the course of his career.

He was then assigned to the Aircraft Branch of the Air Corps Materiel Division, and in October 1935 was appointed chief of the Attack and Observation Engineering Unit there.

[1] Timberlake entered combat operations in World War II as a colonel in North Africa in charge of IX Bomber Command.

Timberlake assumed command of the 8th Air Force in 1946 before moving to various high level roles in the Army-Navy Munitions Board from late 1946 to 1950.