Where in Chicago area is Camp Douglas located?

Is there anyway to check know rolls? I'm looking for clues on this man.

Benjamin Bennett Graves. b. abt 1831 shows up in various documents as Bennett F. Graves or William Bennett Graves or Bennett B., Benjamin Bennett...

MILITARY: Civil War - Capt' Beauregard's Co. South Carolina Light Artillery (Ferguson Co., Lt. Art'y) Confederate.
Enlisted 16 November 1862.
Missing since 25 November 1863.
Captured at Ringgold, Ga. on 1 December 1863.
Sent to Louisville, Ky on 13 December 1863 for exchange.
Sent on to Rock Island, Ill. on 16 December 1863.
Then transferred to Naval rendezvous at Camp Douglas, Chicago, Ill. on 25 January 1864.
Possibly died in Civil War.