It was Burnside's plan, immediately upon the ex¬plosion, to put in his colored division, supporting the attack by his white divisions—the corps itself being supported by other corps upon either flank.    Upon gaining the crest of the works shaken by the explosion, the attacking columns would divide and take the enemy's line in reverse.    The colored troops were drilled for two or three weeks with especial refer¬ence to the duty they were expected to perform, and their commanders carefully reconnoitered the ground.    General Ferrero and his officers became quite enthu¬siastic in the prospect of service which promised dis¬tinction.    But when this plan of attack was submitted to Generals Grant and Meade, they did not give to it their approval.    General Grant afterwards had the frankness to say that he believed that, if Gene¬ral Burnside had put his colored division in front, "it would have been a success."    But at the time when this opinion would have had weight, he disap¬proved that movement.    The colored troops were distrusted at headquarters.    The formation of the column of attack was not approved, and on the af¬ternoon of the 29th of July, Burnside found that his plan of attack, which had been carefully studied and elaborated, must be given up.    One of his white di¬visions—harassed and worn as they had been by the hard service of the summer and by the necessity of perpetual watching an enemy in very close prox¬imity—must make the assault.    Burnside allowed his division commanders to draw lots for the leading position.    By an extraordinary fatality the lot fell upon General Ledlie—the least experienced and the least competent of the three.    We can only look upon this mode of selection as an unfortunate error of judgment. Burnside should have given to his best and most trusted subordinate the duty of leading the attack.    Thwarted in his first choice of the col¬ored troops, he should have put the best of his white divisions forward.    In cases of this kind it does not answer to trust to chance.    The mine was to have been exploded at 3 o'clock on the morning of the 30th.    The fuses were ignited promptly, but the connections had become damp, and the fire would not communicate.    The failure was remedied as speedily as possible, and at sixteen minutes before five o'clock, the mine was success¬fully sprung.    An entire six-gun battery, and its garrison of two hundred men and more, with all their paraphernalia were thrown into the air and fell again in inextricable confusion.    A huge chasm two hun¬dred feet long, fifty feet wide and twenty-five feet deep, with sand, clay, broken gun-carriages, cais¬sons and human beings remained—a scene of ruin and desolation.    The enemy was taken completely by surprise.    "The troops in the immediate vicinity," says the author of Lee and his Campaigns, "were considerably demoralized by the sudden and appall¬ing explosion."    Ledlie's division was immediately ordered in and made for the breach.    The troops entered the chasm, but by some unhappy error they were permitted by their leaders to remain there.    In point of fact they had no leader, for General Ledlie did not go with his command.    Whether they were surprised themselves by the havoc that had been made, or were disposed to stop and make captures of the half-buried men who were crying for help; whether there was any misunderstanding of orders, or some strange feebleness of will in the immedi¬ate direction fell upon them and paralyzed their ef¬forts for the moment, we cannot tell.    "Had they advanced beyond the crater," says the author I have just quoted, "they might have carried the line, for the Confederates had not yet recovered from their surprise.    To the astonishment of every one," he adds, "they huddled into the crater and sought shel¬ter there and behind the breastworks."    Other troops were at once sent in, and last of all, the colored di¬vision.    But they all, with the exception of Potter's division and the colored troops, crowded down into the crater at once.    Potter and Ferrero got their commands beyond, but they were speedily driven back, and, mingling with the others, increased the contusion.    All accounts agree, that if the leading division had made at once for the crest of the hill beyond, the rebel line would have been broken, and the other divisions following in support would have, in all probability, won a decisive victory.    But after the first half hour had passed, and the enemy had recovered from his surprise, while the troops re¬mained in the crater without advancing, the day was hopelessly lost.    It would seem, however, that some strong demonstration might have been made by those portions of our army that were formed on either flank of the Ninth Corps, by which the suffering troops in the crater could have been extricated from their deadly position.    General Meade declined to go to the front, although solicited to do so by General Burnside and other officers.    Grant went forward, and seeing how hopeless the enterprise was, ordered the withdrawal of the troops.    Thus ended in disaster what, in its inception, was as promising an attack as the Army of the Potomac ever made.    The disagree¬ment between the generals in regard to the plan of attack before it was made, was extremely unfortu¬nate.    General Meade was punctilious, and, as Gen¬eral Badeau says, lost his temper on the day of bat¬tle.    General Burnside naturally felt great chagrin that his arrangements, which he had carefully made, I should be so completely set aside within twelve hours of the time at which the attack was to be made.    Still he loyally set himself to the task and would have accomplished it had not the leading divis¬ion delayed too long in its advance.    It could hardly have been expected that Burnside himself would lead the way.    A court of inquiry investigated the mat¬ter and blamed Burnside and several of his officers by name.    The committee on the conduct of the war subsequently took up the case and exonerated Burnside.    General Grant, in his testimony, blamed not only General Ledlie for his inefficiency, but also "his seniors, for not seeing that he did his duty, all the way up to" himself.    He considered the operation as most promising in results.    "Such an opportunity for car¬rying fortifications," said he, "I have never seen, and do not expect again to have."    It is a significant fact, nevertheless, that it was with great difficulty that Lieutenant-colonel Pleasants could obtain approval at headquarters for the project of mining the enemy's works.    This was the end of Burnside's military service.    He was granted leave of absence on the 13th of August and immediately left the army for his home.    Mr. Lincoln refused to accept his resignation, but on the accession of Mr. Johnson, it was again tendered, and on the 15th of April, 1865, was finally accepted.