The Mud March was an abortive offensive by Union Major General Ambrose Burnside and his Army of the Potomac in January 1863 during the American Civil War. Burnside had been repulsed by the Army of Northern Virginia under Confederate General Robert E. Lee in Burnside's first attempt to cross the Rappahannock River during the Battle of Fredericksburg in December 1862. The Mud March was Burnside's second attempt at crossing the Rappahannock to capture the Confederate capital of Richmond, Virginia.

Ambrose Everett Burnside was an American army officer and politician who became a senior Union general in the Civil War and three-time Governor of Rhode Island, as well as being a successful inventor and industrialist.