View our animated map of the July 21, 1861 Battle of Bull Run (First Manassas). Learn about the strategies and the movements of the two armies as they engage in the first major combat of the American Civil War. Watch McDowell's Federal army make its bold flank attack. Witness Stonewall Jackson establishing a stout line atop Henry Hill and the final Confederate assaults on Chinn Ridge. Bull Run (First Manassas) would become the largest and bloodiest battle in American history up to that time.