Baltimore and the headquarters of the army, with posts of observation toward Williamsport, Emmitsburg, and Harper's Ferry. As soon as I heard the cannon at Gettysburg on July 3, the dispositions of the troops were changed from a passive to an active state. I directed a detachment of cavalry to be sent by Colonel McReynolds to Falling Waters, to reconnoiter for a pontoon bridge, said to be there, and to destroy it. This expedition, under Major Foley, Fourteenth Pennsylvania Cavalry, was executed with great judgment and perfect success. The report of that officer is appended. * Following on this, I sent Morris' brigade, a battery of artillery, and a detachment of cavalry, in all about 4, 000 strong, to advance as far as South Mountain and Crampton's Pass, which to occupy and hold. One regiment of the Maryland Brigade was posted on the Emmitsburg road, with a detachment of cavalry at the latter place. On july 5, another expedition was sent to Harper's Ferry, where the enemy had floored the railroad bridge, and was crossing the river in small detachments. Under the direction of Major [H. A.
Cole, the trestle-work on each side of the bridge was destroyed; also the bridge over the canal. On the 6th, I was ordered to reoccupy with a portion of my command Maryland Heights. Kenly's brigade was detached for that purpose, and subsequently Briggs' brigade, and afterward, on the 7th, the brigade of Naglee. The Seventh New York City Guards, under Colonel Lefferts, I directed to garrison the city of Frederick, appointing that officer military governor. The troops which had been left at Harper's Ferry rejoined my command on this date, under Brigadier-General Elliott. With these and General Morris' brigade, and the three batteries of artillery, I joined the Third Corps, and assumed command on July 9. The cavalry was directed to report to the chief of that arm. The Third Corps in the movements toward and in the vicinity of Williamsport, on July 10, 11, 12, and 13, was held in reserve, but after the army assembled at Harper's Ferry it took the advance in the passage of the Potomac and in the marches, preceding the entrance of Manassas Gap, through Hillsborough, Woodgrove, Upperville, and Piedmotn, at which places it bivouacked after a day's march. At Upperville, on the evening of July 22, I was ordered to move upon Manassas Gap, to hold two divisions at Piedmont, and send forward a third to re-enforce Brigadier-General Buford, who had been directed to seize the Gap. The First Division, under Brigadier-General Ward, arrived at Linden Station, in the Gap, at 11 p. m., and, in conjunction with the cavalry, took possession of the Gap. The Second and Third Divisions pushed forward at early daylight on the 23d, the head of column arriving at Linden about 9 a. m. The cavalry had been relieved at that time by General Ward, whom I directed to send out a small battalion of skirmishers to feel the enemy and to compel him to show his pickets on the heights as well as in the ravines. In the meantime a line of skirmishers was deployed from the right to the left in the Gap, covering the whole front; the ridge roads were covered by artillery and infantry, and my flanks and rear as well guarded as the rugged nature of the country permitted. These dis-