Born in Kimball, South Dakota, Miller moved 35 miles northeast to Huron in 1914 and began working as an auto mechanic. Two years later Miller enlisted in the U.S. Army, seeing action in the Mexican expedition into Mexico, launched after repeated bandit raids across the border. After the United States entry into World War I, Miller served in France with the 18th Infantry Regiment and, decorated for valor and bravery, he rose to the rank of color sergeant by the war's end.