Before the Antietam Campaign:
From Pittsburg, he was 1st Lieutenant of the Pittsburg City Guards, before the War. He enlisted as 1st Lieutenant of Company K, 12th Pennsylvania Infantry in April 1861. After that regiment's service was complete, in August, he was active in recruiting the 4th Pennsylvania Cavalry, and was commissioned Lt Colonel at its organization 18 October 1861. He was made Colonel of the Regiment 12 March 1862 when Colonel Campbell resigned to take command of the 5th PA Cavalry.

On the Antietam Campaign, because Brigade commander General Averill was ill, command of the brigade devolved on Colonel Childs, and of the regiment on Lieutenant Colonel Kerr.

In the Antietam Campaign:
"The brigade crossed the Antietam with the troops upon the left, and was posted in front of the Stone Bridge, where the Fourth supported Clark's Battery and held the line upon its right. A single solid shot, which fell in the midst of the squadron supporting these guns, killed two men and four horses. Colonel Childs was among the killed in this battle. He had completed an inspection of the skirmish line, and was with the staff, under cover of a hill, in a place of comparative safety. While there chatting pleasantly, he was struck by a solid shot on the right hip. The ball passed across him, throwing him from his horse and disemboweling him. He was at once carried to better shelter, when conscious of his certain death, he first arranged his military duties, sending Captain Hughes to report to General Pleasanton, and another of his aids to Lieutentant Colonel Kerr, that he might take command of the brigade. He then dispatched an orderly to Dr. Marsh, to tell him " if not attending to any one whose life could be saved, to come to him, as he was in great pain." Lastly, he called Captain Henry King, Assistant Adjutant General, to whom he delivered his last messages to his family, and wishes as to his property. He lived forty minutes after he was struck, but was unconscious during the last twenty."
(from Bates)

James H Childs