At 4:44 A.M. on July 30, 1864, the explosives blew with what must have been the loudest sounds of the entire war. The Pennsylvania miners had done their work well, even expertly. The explosion created a crater twenty feet long and sixty feet wide, and it was—in some places—twenty feet deep.

General Ambrose Burnside—who had commanded at Fredericksburg—had charge of the assault, and three divisions of Northern soldiers attempted to pour into the Crater. The explosion had shaken the Confederate defenders—literally as well as figuratively—and for a few brief moments, it was possible that a breakthrough would be achieved.