Before the Antietam Campaign:
After his graduation* [from West Point] he returned home, and occupied himself in the peaceful life of a farmer. When President Lincoln issued his call for seventy-five thousand men, A. H. Colemnn responded, and in forty-eight hours he raised Company D, Eleventh Ohio Volunteer Infantry, and went with them to Columbus, Ohio, where he was unanimously chosen captain of the company …".

He "was promoted to the rank of lieutenant-colonel on the 9th of January, 1862"
(from Miami History)

In the Antietam Campaign:
"and I cannot refrain from paying the poor tribute of honorable mention to the memory of Lieutenant-Colonel Coleman, commanding Eleventh Regiment Ohio Volunteer Infantry. He had acted the part of a hero at the recent fight at Bull Run Bridge and at the battle of South Mountain. He met a hero's death in the battle of the 17th of September."
(from Col Scammon's report)

Augustus H Coleman