US Civil War mines. Drawing showing the discovery of Confederate mines (one in foreground) on the Potomac River near Aquia Creek, northern Virginia, USA, on 7 July 1861 during the US Civil War. In the background are Union ships and a rowing boat sent out to examine one of the mines. This drawing by Alfred Rudolph Waud (1828-1891) was based on a photograph by James F. Gibson. At upper left is the gunboat USS Thomas Freeborn. In the far background is the sloop-of-war the USS Pawnee. These ships are all part of the Potomac Flotilla that patrolled the waters in and around Chesapeake Bay.