Bull Run, Second Battle of, or Second Manassas, August 28–30, 1862, a Confederate victory in the American Civil War. The Confederate forces, ably led by Generals Robert E. Lee and “Stonewall” Jackson, defeated the Union troops under General John Pope. After two days of stubborn fighting the Northern forces retreated with heavy losses in men and equipment. General Pope was transferred to Minnesota and General George B. McClellan took over his command. General Lee followed up his victory with an invasion of the North that was halted at Antietam, in Maryland.