Born in Illinois. A resident of Rossville, Allamakee County, Iowa when he enlisted in the 27th Iowa Infantry for three years. Mustered in as a Private in Company I on 5 Sep 1862. Received a slight head wound on 9 Apr 1864 at Pleasant Hill, Sabine Parish, Louisiana. Promoted to 7th Corporal 15 Oct 1864, and 6th Corporal 26 Mar 1865. Mustered out at Clinton, Clinton County, Iowa. He was a member of Custer Post No. 6 of Tacoma, Pierce County, Washington, and also of Luther C. Ladd Post No. 17 of Puyallup, Pierce County, Washington. Coffman served as Commander of the Ladd Post in 1890, 1897 and 1902. He also served as Commander of the Department of Washington and Alaska for the 1921-22 term. He died in Tacoma, Washington.