A division of African-American troops in Burnside's Ninth Corps was to have led the attack that followed the explosion of the mine. But just hours before the assault, Union army commander George G. Meade changed the plan. The result: chaos and tragedy.
For weeks the black troops had rehearsed their role as spearhead of the assault. But late on July 29, fearing public outcry should the African-American troops suffer heavy casualties, Meade ordered Burnside to pick another, all-white division to lead the attack. The unprepared white troops - and the attack - faltered.
The last-minute decision did not spare the black troops the horror of the day. The division joined the battle at 8 a.m., when the fighting had degenerated into a brutal, confused brawl. More than 200 black troops died. Another 400 were missing - many of them dead too. No Union division in the battle suffered more.
(sidebar) Maj. Gen. Ambrose E. Burnside (left) advocated using African-American troops to lead the assault. When overruled, he let his division commanders draw straws for the assignment. By this method, Burnside's weakest division commander, James Ledlie, was chosen.