during the night to the rear of the Eighteenth Corps, to relieve that corps in the line, that it might be foot-loose in the assault to be made. The other two divisions of the Second Corps and Sheridan's cavalry were crossed over on the night of the 29th, and moved in front of Petersburg. On the morning of the 30th, between 4 and 5 o'clock, the mine was sprung, blowing up a battery and most of a regiment, and the advance of the assaulting column, formed of the Ninth Corps, immediately took possession of the crater made by the explosion, and the line for some cause failed to advance promptly to the ridge beyond. Had they done this, I have every reason to believe that Petersburg wold have fallen. Other troops were immediately pushed forward, but the time consumed in getting them up enable the enemy to rally rom his surprise (which had been complete) and get force to this point for its defense. The captured line thus held being untenable and of no advantage to us, the troops were withdrawn, but not without heavy loss. Thus terminer in disaster what promised to be the most successful assault of the campaign.*
Immediately upon the enemy ascertaining that General Hunter was retreating from Lynchburg by way of the Kanawha River, thus laying the Shenandoah Valley open for raids into Maryland and Pennsylvania, he returned northward, and moved down that valley. As soon as this movement of the enemy was ascertained, General Hunter, who had reached the Kanawha River, was directed to move hit troops without delay, by river and railroad, to Harper's Ferry'; but owing to the difficultly, by river and railroad, to Harper's Ferry; but owing to the difficulty of navigation, by reason of low water and breaks in the railroad, great delay was experienced in getting there. It became necessary, therefore, to find other troops to check this movement of the enemy. For this purpose the Sixth Corps was taken from the armies operating against Richmond, to which was added the Nineteenth Corps, the, fortunately, beginning to arrive in Hampton roads from the Gulf Department, under orders issued immediately after the ascertainment of the result of the Red River expedition.
The garrisons of Baltimore and Washington were at this time made up of heavy artillery regiments, 100-day's men, and detachments from the Invalid Corps. One division, under command of General Ricketts, of the Sixth Corps, was sent to Baltimore, and the remaining two divisions of the Sixth Corps, under General Wright, were subsequently sent to Washington. On the 3rd of July the enemy approached Martinsburg; General Sigel, who was in command of our forces there, retreated across the Potomac at Shepherdstown, and General Weber, commanding at Harper's Ferry, crossed the river and occupied Maryland Heights. On the 6th the enemy occupied Hagerstown, moving a strong column toward Frederick City. General Wallace, with Ricketts' division and his own command, the later mostly new and undisciplined troops, pushed out from Baltimore with great promptness and met the enemy in force on the Monocacy, near the crossing of the railroad bridge. His force was not sufficient to insure success, but he fought the enemy nevertheless, and although it resulted in a defeat to our arms, yet it detained the enemy and thereby served to enable General Wright to reach Washington with two divisions of the Sixth Corps, and the advance of the Nineteenth Corps before him. From Monocacy the enemy moved on Washington, his cavalry advance reaching Rock-
*For subordinate reports of operations against Petersburg and Richmond from June 13 to July 31, 1864, see Vol. XL, Part I.