On July 30, 1864, men from Maj. Gen. Ambrose Burnside's IX Corps ignited a mine underneath the Confederate lines at Petersburg. Union infantry charged into the breach, including United States Colored Troops (USCTs) only to be met by arriving Confederate reinforcements. The combat that ensued was some of the most vicious of the war. The Federals were ultimately driven back with heavy loss. The Confederates consolidated their lines and the engagement ended in a Union disaster.