The IX Corps was prominently connected with the siege because of its role in the infamous Battle of the Crater, in which a lengthy mine shaft was dug from its line to under the Confederate works. This mine, which was excavated by the coal miners of 48th Pennsylvania, Potter's Division, was successfully exploded with four tons of gunpowder, resulting in an enormous crater, but the assault that followed was a failure. Just before the assault, Grant and Meade directed Burnside to replace Ferrero's black division with Ledlie's white division, fearful of the political consequences of using black troops at the forefront of a major assault. But Ledlie's troops were not trained for the assault and Ledlie himself remained in the rear area, inebriated. The assault was a fiasco, in which Union soldiers charged into the crater, becoming trapped there, easy targets for the Confederates along the crater's rim. Ferrero's black regiments went into action in the rear and fought well, but had no chance for success. The losses in the IX Corps at the crater were 473 killed, 1,646 wounded, 1,356 missing; total, 3,475. Immediately after this engagement, General Ledlie was relieved from command of the 1st Division, and Brig. Gen. Julius White, of the XXIII Corps, was assigned to Ledlie's place.
