In the summer of 1916, the 4th South Dakota Infantry of the National Guard arrived in San Benito, Texas, to defend the U. S. border against raids by Pancho Villa's Army during the Mexican Revolution. Placed into the First Separate Brigade with the 22nd U. S. Infantry, 1st Louisiana and 1st Oklahoma, the troops saw no combat. However, the men took place in large-scale training maneuvers to prepare for the United States' potential involvement in World War I. The 4th returned home in March 1917 and was released from active duty. When the country entered World War I, the regiment broke up into divisions that fought in France.
Source:
The National Guard. " Today in Guard History (July) ." Accessed April 19, 2011.
From the guide to the Fourth South Dakota Infantry, San Benito, Texas, Collection 87-164., 1916-1917, (Dolph Briscoe Center for American History, The University of Texas at Austin)