He enlisted as a substitute in August 1863 and by September 29, 1864, was serving as a First Sergeant in Company F of the 6th United States. Colored Infantry Regiment. He was mustered out in September 1865. Before the war, he worked as a coal miner in Western Pennsylvania.
He went to Homestead, Pennsylvania after the war and for a time, served as the night watchman at the Pittsburgh Police stables.
Alexander Kelly married but never had children. He died at age 67 and was buried in Saint Peters Cemetery, Pittsburgh, Pennsylvania.
The painting is scheduled to be unveiled June 24, 2013 at the Union League of Philadelphia.