Cameron was assigned to command the Maneuver Camp at
Fort Benjamin Harrison at the start of U.S. preparation for entry into
World War I. He subsequently organized officer training in the Army's Southern Department, and then commanded the
5th Cavalry Regiment. In 1917 he was assigned to command of the 3rd
Brigade in the Army's
15th Cavalry Division. When the plan to field Cavalry divisions was dropped in favor of creating all Infantry divisions, Cameron was assigned as commander of the
25th Cavalry Regiment. Cameron was promoted to temporary
brigadier general and briefly commanded 78th Infantry Brigade,
39th Infantry Division and 80th Brigade,
40th Infantry Division. From September to December 1917 he commanded the 40th Infantry Division. He was promoted to temporary
major general in December 1917 and assigned to command of the
4th Infantry Division. He was the division's first commander, and led it from its organization at
Camp Greene,
North Carolina through most of 1918, including the
Saint-Mihiel Campaign and the start of the
Meuse-Argonne Campaign. He is also credited with designing the division's shoulder sleeve insignia. From August to October 1918 Cameron commanded the
V Corps, and led it during the latter portion of the Meuse-Argonne campaign. He was relieved after the Battle of Montfaucon, supposedly because V Corps did not accomplish their objective on the first day of fighting, but possibly because he argued with
Hugh Drum. (
John J. Pershing was attempting to simultaneously command
First Army and the
American Expeditionary Forces. As First Army Chief of Staff, Drum, then a
colonel, was at times its de facto commander. During the Battle of Montfaucon, he pressed Cameron during a phone call, and Cameron told him "you can't talk to me like that." Cameron was of the view that Drum reported the conversation to Pershing, and that it led to Cameron's relief.) In October 1918 he was succeeded at V Corps by
Charles P. Summerall, a Pershing protégé, and returned to command of the 4th Division. Later in October Cameron was designated to return to the United States to organize and train additional units for fighting in France, but the end of the war eliminated the need for more soldiers. ==Post World War I==