Armstrong served as a private in Company “E” of the 10th Regiment of West Virginia Infantry Volunteers. He enlisted January 26, 1862 in Tyler County, WV. He mustered into service on April 7, 1862 at Clarksburg. Originally papers were filed saying he was killed July 18, 1864 at Snickers Ferry, VA, but must have been captured during that battle. In fact, in his father’s 1869 Application for Father’s Army Pension, it was stated that Armstrong “was killed while crossing the Shenandoah River at Snicker’s Ferry.” 768 Snickers Ford was part of the battle of Cool Spring, fought on July 18, 1864 on the Shenandoah River in Clarke County, VA. The battle resulted in a Confederate victory.908

Armstrong actually died as a prisoner of war, January 6, 1865 in Division No. 2, General Hospital, Danville, VA. The cause of death was chronic diarrhea. (from the Surgeon General’s Office, Record and Pension Division, Feb. 11, 1871 and other papers)768