On 9 March 1916, Francisco ‘Pancho’ Villa ordered around 500 of his revolutionaries to make a cross-border attack against Columbus, New Mexico. The raid was conducted largely because of the U.S. government's official recognition of the Carranza regime. They attacked a detachment of the 13th Cavalry Regiment, seizing 100 horses and mules, and setting part of the town on fire. 18 Americans and about 80 Villistas were killed.
The attack resulted in the U.S. sending 12,000 soldiers into Mexico to apprehend Villa and almost sparked off a full-blown war between the nations after Carranza objected to the presence of American soldiers on Mexican land.