On July 30, 1864, at the Battle of the Crater, the Union’s ingenious attempt to break the Confederate lines at Petersburg, Virginia, by blowing up a tunnel that had been dug under the Rebel trenches fails. Although the explosion created a gap in the Confederate defenses, a poorly planned Yankee attack wasted the effort and the result was an eight-month continuation of the siege.

The bloody campaign between Union General Ulysses S. Grant and Confederate Robert E. Lee ground to a halt in mid-June, when the two armies dug in at Petersburg, south of Richmond. For the previous six weeks, Grant had pounded away at Lee, producing little results other than frightful casualties. A series of battles and flanking maneuvers brought Grant to Petersburg, where he opted for a siege rather than another costly frontal assault.

In late June, a Union regiment from the 48th Pennsylvania Infantry began digging a tunnel under the Rebel fortifications. The soldiers, experienced miners from Pennsylvania’s anthracite coal regions, dug for nearly a month to construct a horizontal shaft over 500 feet long. At the end of the tunnel, they ran two drifts, or side tunnels, totaling 75 feet along the Confederate lines to maximize the destruction. Four tons of gunpowder filled the drifts, and the stage was set.

Union soldiers lit the fuse before dawn on July 30. The explosion that came just before 5:00 a.m. blew up a Confederate battery and most of one infantry regiment, creating a crater 170 feet long, 60 to 80 feet wide, and 30 feet deep. As one Southern soldier wrote, “Several hundred yards of earth work with men and cannon was literally hurled a hundred feet in the air.” However, the Union was woefully unprepared to exploit the gap. The Yankees were slow to exit the trenches, and when they did the 15,000 attacking troops ran into the crater rather than around it. Part of the Rebel line was captured, but the Confederates that gathered from each side fired down on the Yankees. The Union troops could not maintain the beachhead, and by early afternoon they retreated back to their original trenches.

This failure led to finger pointing among the Union command. General Ambrose Burnside, the corps commander of the troops involved, had ordered regiments from the United States Colored Troops to lead the attack, but the commander of the Army of the Potomac, George G. Meade, nixed that plan shortly before the attack was scheduled. Fearing that it may be perceived as a ploy to use African-American soldiers as cannon fodder, Meade ordered that white troops lead the charge. With little time for training, General James H. Ledlie was left to command the attack.

The Battle of the Crater essentially marked the end of Burnside’s military career, and on April 15, 1865, he resigned from the army.