In the background rises the dome of the Capitol which this regiment remained to defend until it was ordered to Petersburg, in 1864. It appears in parade formation. The battery commander leads it, mounted. The battery consists of six pieces, divided into three platoons of two guns each. In front of each platoon is the platoon commander, mounted. Each piece, with its limber and caisson, forms a section; the chief of section is mounted, to the right and a little to the rear of each piece. The cannoneers are mounted on the limbers and caissons in the rear. To the left waves the notched guidon used by both the cavalry and light artillery.

This photograph shows the flat nature of the open country about Washington. There were no natural fortifications around the city. Artificial works were necessary throughout. Fort Whipple lay to the south of Fort Corcoran, one of the three earliest forts constructed. It was built later, during one of the recurrent panics at the rumor that the Confederates were about to descend upon Washington. This battery of six guns, the one on the right hand, pointing directly out of the picture, looks quite formidable. One can imagine the burst of fire from the underbrush which surrounds it, should it open upon the foe. At present it is simply drilling.