During that engagement, nearly 10,000 slaves left area plantations and city households to gain freedom by crossing the Rappahannock River to Stafford County and join the Union lines, part of a movement by slaves throughout the South in wartime. John Washington, a literate slave who shortly crossed to freedom, wrote later about people watching the approach of Union troops across the river from Fredericksburg: "No one could be seen on the street but the colored people. and every one of them seemed to be in the best of humors."