Insignia, the figure "18" superimposed on a green cactus plant, under which is written "Noli me tangere." Organized at Camp Travis, Texas on August 21, 1918. The 19th and 35th Regular Army Infantry Regiments were assigned to this division and these regiments furnished the nucleus for the organization of the other two infantry regiments of the division. The artillery brigade of this division was organized at Camp Stanley, Leon Springs, Texas, on August 14, 1918., from the 303d, 304th and 305th National Army Cavalry Regiments. This brigade joined the 18th Division at Camp Travis at the end of August. The engineer regiment of the division was organized at Camp Humphreis in the early part of September, 1918, and joined the division at Camp Travis on November 9, 1918. All units of the division except the engineer train were organized by the middle of October and undergoing intensive training in preparation for service overseas. Demobilization of the division commenced on January 17, 1919, and demobilization of all organizations except those belonging to the Regular Army was completed of February 14, 1919.

Brigadier General G. H. Estes was the commanding general.

The division was composed of the following organizations: 18th Hqs. Troop, 52d Machine Gun Bn., 35th Inf. Brig. (19th and 85th Inf., 53d Machine Gun Bn.), 36th Inf. Brig. (35th and 36th Inf, 54th Machine Gun Bn.), 18th Fld. Arty. Brig. (52d, 53d, and 54th Fld. Arty., 18th Trench Mortar Battery), 218th Engrs., 18th Train Hqs., and M.P., 18th Amm. Train, 18th Supply Train, 18th Sanitary Train (Field Hospitals and Amb. Cos. No. 269, 270, 271 and 272).