Forrest arrived at Camp Meade MD and Joined the 316th Infantry Supply Division on 19 Sept 1917. He left Camp Meade on 7 July 1918 for Hoboken NJ, then to France. He left St. Nazaire France on 16 May 1919 and arrived at Snyder Ave Warf in Philadelphia on 29 May 1919.
Forrest served as a Private in the U.S. Army. He was assigned to Company G 316th Infantry (Supply) Division which was a part of the 158th Infantry Brigade, serving under the 79th Division National Army.
Forrest was involved in the Meuse-Argonne Offensive from 26 Sept to 03 Oct 1918. He was in the first assult with eight other divisions. he relieved the 26th division at Troyon Sector from 08 Oct to 25 Oct 1918. He then was apart of the second phase of the Meuse-Argonne offensive from 29 Oct to 11 Nov 1918.