I think you might the sides here mixed up. The Unoin army got their asses kicked at the first battle of Bull Run. That was the first battle of the war just outside of Washington DC. Lee was stunned when the Union army broke and ran. The Confederate chased the Union army and the civilian spectators back to the edge of town.
Nope, found it... From "Civilwarhome.com"
Lesser battles are famous for their casualties. At Franklin, Tennessee, November 30, 1864, General Hood's Confederates lost over 6,000 of 21,000 effectives -most of them in about two hours. Six Confederate generals died there.
Mark