Heyl was commissioned in the 23 Infantry Regiment in October 1873, and served as regimental adjutant from 1890 to 1891. During the Spanish–American War, he was promoted to major and assistant adjutant general in May 1898, and became an inspector general of volunteers in July. He was again promoted to lieutenant colonel in December 1899, and to colonel in July 1902.
He retired in November 1904.
Heyl was buried in Arlington National Cemetery.