It was just after 3 am on Saturday, July 30, 1864. A month of relative quiet along a two-mile stretch of Union and Confederate trench lines immediately east of Petersburg, Virginia, was about to come to an explosive end. In the aftermath of several earlier Federal attacks on the strategically vital city in mid-June, a portion of Maj. Gen. Ambrose Burnside’s IX Corps picket line lay only 400 feet from Elliot’s Salient, a highly fortified position on high ground that formed an angle protruding out from the main Confederate line, commanded by Maj. Gen. Bushrod Rust Johnson.

To support the defenders’ artillery and mortars, a second line, or “cavalier trench,” had been dug close behind the main redoubt. Elliot’s Salient boasted four smoothbores of Lt. Col. William Pegram’s battery and was backed by two regiments of veteran infantrymen of Brig. Gen. Stephen Elliot’s South Carolina Brigade. Across a north-south ravine from Elliot’s Salient were trenches occupied by the troops of Lt. Col. Henry Pleasants’ 48th Pennsylvania Volunteer Regiment, many of them coal miners in civilian life.

In an unprecedented feat of excavation, and after coming up with the idea on their own, the men of Pleasants’ regiment dug a 511-foot-long tunnel right up to the Rebel works, 20 feet underground, and packed it with 8,000 pounds of highly explosive black gunpowder. After the mine was exploded at 3:30 am and a concentrated Union artillery barrage hit the two-mile stretch of Rebel works, a massive assault by 14,000 Union troops was planned to exploit the expected breach blown in the enemy’s line. If the Federals could swarm past the ruptured strongpoint and take the high ground 500 yards behind it, where Blandford Church’s cemetery was located, the city of Petersburg, terminus of four railroads and Richmond’s crucial lifeline to the Deep South, could be captured before the day was done. With Petersburg in Union hands, the Confederate capital of Richmond would surely soon fall as well. After a series of Union thrusts against Petersburg—flanking movements rather than costly frontal assaults—from June 9 to June 24 had failed and General Robert E. Lee had reinforced the Confederate defenders, a month-long lull fell over the trench lines. After the carnage at the Wilderness, Spotsylvania Courthouse, North Anna, and Cold Harbor, Union commander in chief Ulysses S. Grant had continued trying to maneuver Lee into position for an open-field battle to destroy the Army of Northern Virginia, but Lee responded by fighting behind an elaborate trench system, hoping to hold out long enough to discourage the Northern people into forcing their leaders to make peace with the South. Lee had remarked to Maj. Gen. Jubal Early, “We must destroy this army of Grant’s before he gets to the James River. If he gets there, it will become a siege, and then it will be a mere question of time.”

Neither Grant nor the commander of the Army of the Potomac, Maj. Gen. George Meade, was especially optimistic about the mine’s potential usefulness—Meade termed it “clap-trap and nonsense”—but they allowed it to proceed as a way to keep the bored soldiers busy. In late July, after problems in the Shenandoah Valley and a Union setback at the First Battle of Deep Bottom put pressure on Grant to break the stalemate at Petersburg, the mine’s potential took on a whole new significance to the Union high command. On July 26 Grant sent Maj. Gens. Winfield Hancock and Phil Sheridan on a diversionary attack against Richmond in an effort to get Lee to fatally strip his Petersburg defenses. Hancock’s II Corps and Sheridan’s two cavalry divisions failed to crack the Confederate fortifications, but they achieved their objective. After Lee ordered 20,000 men north of the James River, General P.G.T. Beauregard, commander of the Department of North Carolina and Southern Virginia, was left with just three divisions at Petersburg, some 18,000 effectives in all.

Meanwhile, Pleasants’ men had come up with a viable alternative to costly frontal assaults and flanking maneuvers: they would go under the ground rather than over it. The 48th got almost no support from Meade or his chief engineer, Major James C. Duane, largely because the mine would have to be longer than 400 feet, a distance that would pose serious ventilation problems. Meade neglected to officially sanction the operation, allowing Duane to refuse the 48th the materials they needed to do the job: tools, timber, wheelbarrows, and sandbags. Left to their own devices, Pleasants’ men went to work anyway using improvised equipment, putting shovel to dirt on June 25.

Pleasants and his 400 men completed the 511-foot shaft on July 17 in just three weeks—a mining miracle. Pleasants then devised an ingenious system to pump fresh air into the entire expanse when ventilation issues arose. Some 320 kegs of gunpowder—8,000 pounds—were placed in twin galleries below Elliot’s Salient, while enemy countermining efforts, belated and uncoordinated, came to naught. Orders were circulated that the mine would be ignited at 3:30 am on the 30th and that a massive infantry attack would commence immediately thereafter. During the night of the 29th, the Federals moved up 164 guns, including heavy mortars, siege guns, and Parrott guns. Also that night almost the entire IV Corps assembled behind the entrance of the mine, assuring the Federals overwhelming numerical superiority at the point of attack.

Three of Burnside’s four divisions, commanded by Brig. Gens. Orlando Willcox, Robert Potter, and James Ledlie, had been on line for 36 days, suffering at least 30 casualties a day from vicious sniping, and were exhausted from life in the trenches—drought, intense heat, bursting mortar shells, and sharpshooters’ bullets. Burnside’s fourth division consisted of two large brigades, nine regiments in all, of United States Colored Troops (USCT) under a white commander, Brig. Gen. Edward Ferrero. They had yet to see combat, but they constituted Burnside’s freshest and largest division and had actually been drilled in preparation for the attack. Burnside had devised an exceptional plan: he would send the USCT division, 4,300 strong, through the gap created by the explosion in standard Civil War deployment—one brigade in front, the second in the rear in support. One regiment from each brigade would leave the attack column and extend the breach by rushing perpendicular to the crater, north and south, while the remaining regiments would advance through and push west toward the Jerusalem Plank Road and Cemetery Hill.

Burnside’s three remaining divisions, their flanks protected, would follow and drive west almost unopposed to help take Cemetery Hill, from which they had a clear shot at Petersburg. A possible rapid end to the war could be envisioned. The attack would mark the first deployment of African American troops into major combat in the Eastern Theater. Beyond the tactical problems of leading so large an assault, though, black soldiers and their white officers had to prepare for combat in which they could expect no mercy if they were captured or left wounded on the field. Colonel John Bross, commander of the 29th USCT, told the press, “When I lead these men into battle, we shall expect no quarter, and shall not ask for quarter.” Burnside was in high spirits; not only did he have units from two other corps standing by to help exploit the breakthrough if necessary—Maj. Gen. Gouverneur K. Warren’s XVIII Corps and Maj. Gen. Edward Ord’s X Corps—but he would have 144 field guns in support and all or part of another corps, Hancock’s, which might return from north of the James River in time for the battle.

The day before the attack, Meade, after consulting with Grant, stunned Burnside by ordering him to spearhead the attack with a white, battle-tested division, a radical change that would have catastrophic repercussions. Grant and Meade feared political controversy if the black division was annihilated, with Grant fretting that they would be accused of “shoving these people ahead to get killed because we did not care anything about them.” Rather than choosing the best of his three other divisions to lead the attack, Burnside went into a funk after he was unable to get the order rescinded. When none of his three remaining division commanders volunteered to lead the assault, Burnside had them draw straws. Ledlie, a political general with no military training, and an alcoholic and coward to boot, won the honors—such as they were. Burnside’s willingness to allow possibly the worst general in the Union Army to spearhead the attack rather than one of his more experienced division commanders was a disastrous decision. With his ranks filled with inexperienced reinforcements and artillery units whose gunners were serving as infantrymen, Ledlie’s two-brigade division was the weakest in Burnside’s corps. Apparently, everyone in IX Corps knew of Ledlie’s shortcomings except Burnside. With less than 12 hours remaining before the attack, new plans had to be made. Rather than give Ledlie specific instructions, however, Burnside merely parroted Grant’s order to press forward and take Cemetery Hill at any cost. He then ordered Potter and Willcox to follow Ledlie, one veering to the left and one to the right, to be followed by the black division. He left all other tactical decisions to his subordinates. Ultimately, Burnside and Pleasants would spend the day 400 yards behind the Crater, protected by a 14-gun battery. Meade too remained safely back, another half-mile behind Burnside and Pleasants.