the night of the 29th and moved in front of Petersburg.  On the morning of the 30th, between four and five 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 9th corps, immediately took possession of the crater made by the explosion, and the line for some distance to the right and left of it, and a detached line in front of it, but for some cause failed to advance promptly to the ridge beyond.  Had they done this, I have every reason to believe that Petersburg would have fallen.  Other troops were immediately pushed forward, but the time consumed in getting them up enabled the enemy to rally from his surprise (which had been complete), and get forces to this point for its defence.  The captured line thus held being untenable, and of no advantage to us, the troops were withdrawn, but not without heavy loss.  Thus terminated in disaster what promised to be the most successful assault of the campaign.

Immediately upon the enemy’s ascertaining that General Hunter was retreating from Lynchburg by way of the Kanawha River, thus laying the Shenandoah Valley open for raid 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 his troops without delay, 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 6th corps was taken from the armies operating against Richmond, to which was added the 19th corps, then 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, hundred days’ men, and detachments from the invalid corps.  One division under command of General Ricketts, of the 6th corps, was sent to Baltimore, and the remaining two divisions of the 6th corps, under General Wright, were subsequently sent to Washington.  On the 3d of July the enemy approached Martinsburg.  General Sigel, who was in command of our forces there, retreated across the Potomac at Shepherdtown; and General Weber, commanding at Harper’s Ferry, crossed the occupied Hagerstown, moving a strong column towards Frederick City.  General Wallace, with Rickett’s division and his own command, the latter 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,