David- The Washington Volunteers was a militia unit based in Washington, DC. Most of the men in it were pro southern, and a lot were born in Maryland, but they had to have been living in DC to belong.There is a good article in Century Magazine,on the Cornell Univ site,that was written by General Stone, of Balls Bluff fame, about dealing with Capt Shaeffer, of the National Rifles, another pro-south militia unit in Washington. They came over the Potomac with the Washington Volunteers and ended up in the 1st Va Infantry, while the Washington Volunteers formed Co "H" of the 7th Va, like you said-Barrett