An interesting mix of military and civilian personnel. The guys wearing boots are probably wagon drivers who took the supplies out to the field. The older officer striking a Napoleonic pose is probably the Quartermaster Officer in Charge (OIC). Just to the left in the picture is a man all in black missing an arm, possibly a vet now doing civilian work in the rear area. The young boy is an enigma -- he's wearing a military shell jacket. Perhaps he's a wannabe drummer boy who was deemed to young to send to the front. The youngest drummer boy killed in action was 13 year old Charles King of Pennsylvania, who died at Antietam when a stray shell dropped on his regiment waiting in reserve. He was the regimental drum major.

This is as about as old as Shorpy gets. I've been here for six years, and my first comment was on a Civil War photo, (https://www.shorpy.com/node/12902). Great comments then, great comments now.