This is a terrific old photo from the Library of Congress. It shows camp Brightwood during Civil War. If you’re into the Cultural Tourism D.C. Heritage Trail, you can read a little more about it on their sign at 5704 Georgia Ave. NW.

[Click image for larger, high-quality version.]

Capt. B.S. Brown (left); Lt. John P. Shaw, Co. F 2nd Regt. Rhode Island Volunteer Infantry (center); and Lt. Fry (right) with African American men and boy.
Capt. B.S. Brown (left); Lt. John P. Shaw, Co. F 2nd Regt. Rhode Island Volunteer Infantry (center); and Lt. Fry (right) with African American men and boy.

Source: Library of Congress