Home State: Pennsylvania
Command Billet: Battery Commander
Branch of Service: Artillery
Unit: 1st Pennsylvania Light Artillery, Battery B
see his Battle Report
Before Antietam
He was promoted from 1st Sergeant to 2d Lieutenant June 28, 1861, and to Captain, August 2, 1861.
On the Campaign
"Captain Cooper had a very narrow escape. While directing the fire of the guns [on Poffenbuger's farm, on the morning of he 17th] a solid shot struck his horse and tore it in pieces."
(from Bates)
The rest of the War
Capt Cooper commanded the Battery more than three years, till he was mustered out August 8, 1864, refusing all promotions. He was commissioned Major, September 24, 1864, but had already left the service.
References & notes
Source: Bates, Samuel P>. History of the Pennsylvania Volunteers, 1861-1864, Battery history online at Pennsylvania in the Civil War.