The history of the Arkansas National Guard and World War I begins with the reorganization of the Arkansas State Guard following the Spanish–American War. As a result of difficulties encountered during the mobilization of state militia forces, the United States Congress passed new legislation which resulted in the renaming of the Arkansas State Guard as the Arkansas National Guard. The new federal legislation resulted in increased funding and training for the guard. The newly reorganized Arkansas National Guard was call upon by the President to help defend the border with Mexico in 1916 in response to cross border raids during the Mexican Revolution. The Arkansas National Guard had just returned from the Mexican Expedition in 1917 when it was activated for World War I. As a part of their incorporation in the United States Army, all National Guard units were renumbered in accordance with a federal system. The Arkansas National Guard units were incorporated into the 39th Infantry Division and after training at Camp Beauregard, were shipped to France in August and September 1918. The 39th Division was broken up, with some units being used as replacements for other divisions. Most former Arkansas National Guardsmen returned to the United States in February through June 1919 and were demobilized.