The Battle of Second Bull Run

U.S. General John Pope
This clash began when John Pope’s Federal Army of Virginia moved to destroy Thomas “Stonewall” Jackson’s Confederates near the site of the Battle of Bull Run in July 1861. The remainder of Robert E. Lee’s Confederate Army of Northern Virginia hurried to link with Jackson, while George McClellan’s Federal Army of the Potomac slowly moved to assist Pope.
Lee’s left “wing” under Jackson occupied Manassas Junction, where the Confederates destroyed Federal supplies and threatened to cut communications between Pope and Washington. Pope moved north to stop Jackson, but he was confused about Jackson’s intentions.
Fighting ensued as Pope chased Jackson from Manassas to Centreville, then to Groveton. Meanwhile, the right “wing” of Lee’s army under Lee and General James Longstreet hurried up from the south. Thinking he had Jackson cornered, Pope attacked Jackson’s entrenched Confederates along an unfinished railroad near Groveton.
The Federal attacks were ineffective, mainly because the troops were scattered and exhausted after chasing Jackson for several days in the August heat. By afternoon, Longstreet’s troops arrived to assist Jackson, and the Confederates were in a strong defensive position. Unaware of Longstreet’s arrival, Pope fell back at nightfall and planned to attack again in the morning. Meanwhile, Federal General-in-Chief Henry W. Halleck ordered McClellan to hurry to Alexandria, but McClellan continued his slow troop transfer off the Virginia Peninsula between the York and James Rivers.
The next day, still believing the Confederates were retreating, Pope renewed his attack on Jackson’s left. Jackson’s troops held firm while Longstreet launched a massive counterattack on the right with 25,000 men; this was the largest mass assault of the war. With his supply lines threatened and his flank crushed, Pope was compelled to withdraw to Centreville.
Skirmishing continued into September as Pope gradually fell back and tried to prevent a complete rout. With his withdrawal, the Federals evacuated Fredericksburg and abandoned vast amounts of supplies, and Jackson’s Confederates moved west to Chantilly. McClellan’s feeble attempts to send reinforcements to Pope had no effect, and Pope succumbed to humiliating defeat after having so boldly predicting total victory.