Lincoln replaced McClellan with General Ambrose E. Burnside, who decided to attack Lee at Fredericksburg, Virginia, on the Rappahannock River. The Confederates defended the town from a line of fortified hills called Marye's Heights. On December 13, Burnside's men tried to storm the hills in a brave but hopeless attack. The Northern army retreated. Burnside was relieved of command at his own request.