Photo shows Brigade officers of the Horse Artillery commanded by Lt. Col. William Hays. The Location is just outside of Richmond, the time being after the battle of Fair Oaks/Seven Pines but before the Seven Days. The cannon is a 3 Inch Ordnance rifle.
The officers are, left to right: Lt. Robert Clarke, Capt. John C. Tidball, Lt. William N. Dennison, and Capt. Alexander C.M. Pennington