Finally there came a trembling of the earth, then a bursting forth of volcanic flames and rolling up of dense clouds of smoke. A mountain of rubbish rose in the air. Earth, men, planks, timbers, cannon, shot and shell, were hurled upward and outward! The sight was terribly grand. To add to the frightfulness of the eruption and the grandeur of the spectacle, one hundred guns instantly belched forth their thunders. The Rebels were surprised and panic-stricken for the moment, and ran to escape the falling earth and timbers, leaving their artillery silent. A huge gap had been made in the Rebel works, four or five hundred feet in length and twenty feet in depth.
Success depended upon the immediate occupation of the breach. Ten minutes passed before Ledlie moved, and then he only advanced to the crater. The Rebels offered no opposition. The important point to be gained and held was a ridge four hundred yards beyond. Ledlie still halted in the excavation. Wilcox and Potter soon followed him, and the three divisions became intermixed, and general confusion prevailed. An hour of precious time was lost. Ledlie made no attempt to move in or out, and Potter and Wilcox could not go forward while he blocked the way.
The enemy gradually recovered from their stupor, and began to fire from the hills, and batteries of artillery were brought up on the right and left to enfilade the crater: but not a cannon-shot was fired by the Rebels till after seven o'clock. The supporting brigades meanwhile were crowding upon those in front. The colored troops were ordered forward. They also entered the crater, which only added to the confusion. Potter succeeded in freeing his troops from Ledlie's, and pushed on toward the crest, but being unsupported, he was obliged to retire, driven back by the canister which the enemy poured into his ranks from the new position they had taken on Cemetery Hill. The Rebel fire increased. Eight, nine, ten o'clock passed; their batteries were throwing a concentrated fire of shells and solid shot into the mingled human mass. Mahone's and Ransom's divisions of infantry were hurried to the top of the ridge, and mortars were brought into play, and the crater became a terrible scene of slaughter. Meade, seeing that further attempt to take the ridge would be not only useless, but a waste of life, permitted Burnside to withdraw his troops at discretion. Yet to retire was to run the gauntlet of almost certain death. The space between the abyss and Burnside's breastworks was swept by a cross-fire from the enemy's artillery and infantry. To remain in the crater was sure destruction; to advance was impossible; to retreat the only alternative. Permission was given the troops to retire. By degrees they fled to the rear; but it was two o'clock in the afternoon before the place was wholly evacuated.
Forty-seven officers and three hundred and seventy-two soldiers were killed, one hundred and twenty-four officers and fifteen hundred and fifty-five soldiers wounded, and nineteen hundred missing; a total loss of over four thousand men, and no substantial advantage gained.
The loss of the Rebels by the explosion was very great, as also by the heavy artillery fire.
The causes of the failure, as decided by the Committee on the Conduct of the War, were: the injudicious formation of the troops assaulting; the halting of Ledlie; lack of proper engineers; and the want of a competent head at the scene of assault.
The reasons why the attack ought to have been successful are thus stated:—
"1. The evident surprise of the enemy at the time of the explosion of the mine, and for some time after.
"2. The comparatively small force in the enemy's works.
"3. The ineffective fire of the enemy's artillery and musketry, there being scarcely any for about thirty minutes after the explosion, and our artillery being just the reverse as to time and power.