Gilbreath was promoted to captain in the Cavalry on 15 May 1917, but was transferred to the Quartermaster Corps on 25 July 1917. He was the Chief Disbursing Officer for U.S. Troops in England from 2 September 1917 to 20 October 1917. Moving to France, he was executive officer of Base Section No. 1 at St. Nazaire from 2 November 1o 25 December 1917. After a stint as assistant G-1 of I Corps, he was assistant quartermaster of the 2d Division from 9 April to 25 June 1918, and then the quartermaster of the 4th Division until 30 October. He was promoted to major in the Cavalry on 7 June 1918, lieutenant colonel in the Quartermaster Corps on 11 October 1918, and colonel in the Quartermaster Corps on 5 May 1919. He was Assistant Chief of Supplies Division at Tours and then Paris, from 1 November 1918 to 30 April 1919, and then Chief of Supply Division until 25 September 1919. After a leave of absence, Gilbreath was posted to Washington, D.C., as assistant to the Director of Storage in the office of the Quartermaster General from 16 November 1919 until 31 May 1920, and then as the chief of Administration Division of the Storage Service until 30 June 1920. He reverted to his permanent rank of captain on 30 June 1920, but was transferred to the Quartermaster Corps with the rank of major the following day. He was posted to San Antonio, Texas, as the quartermaster at the San Antonio Depot until 1 September 1921. He attended the School of the Line at Fort Leavenworth, Kansas, and then the Command and General Staff College there in 1922. He transferred back to the Cavalry on 31 March 1925, and attended the Army War College, graduating on 30 June 1927. Gilbreath served with the 2d Cavalry at Fort Riley, Kansas, and then was posted to Washington, D.C., on 15 August 1928 for duty on the War Department General Staff. He returned to Fort Bliss for duty with the 1st Cavalry Division from 15 September 1932 to 1 June 1934, and then at Fort Riley from 4 June 1934 to 5 June 1935. While he was there, he became a member of the Masters of Foxhounds Association of America. Colonel Jonathan M. Wainwright, the assistant Commandant of the Cavalry School there and the Master of the Cavalry School Hunt, invited him to become joint Master. When it came time for him to leave Fort Riley, Wainwright gave him a fox horn and a sporting brake, a two-horse, two-seated open light vehicle.