Constituted 23 June 1918 as the 99th Division.
Organized in October 1918 at Camp Wheeler, Georgia.
Inactivated in November 1918 at Camp Wheeler, Georgia.
Activated in October 1921 with headquarters at Pittsburg, Pennsylvania.
Ordered into active military service 15 November 1942 and reorganized at Camp Van Dorn, Mississippi as the 99th Infantry Division.
Inactivated 27 September 1945 at Camp Patrick Henry, Virginia.
Major General Walter E. Lauer - Assumed command July 1943
Headquarters, 99th Infantry Division
Headquarters Company, 99th Infantry Division
99th Cavalry Reconnaissance Troop
324th Engineer Combat Battalion
393rd Infantry Regiment
394th Infantry Regiment
395th Infantry Regiment
Headquarters and Headquarters Battery, Division Artillery
370th Field Artillery Battalion
371st Field Artillery Battalion
372nd Field Artillery Battalion
924th Field Artillery Battalion
Headquarters, Special Troops
324th Medical Battalion
799th Ordnance Light Maintenance Company
99th Signal Company
99th Quartermaster Company
Rhineland, Ardennes-Alsace, Central Europe