HEADQUARTERS ARMY OF THE POTOMAC,
October 1, 1863.

GENERAL: I have the honor to submit herewith a report of the operations of this army during the month of July last, including the details of the battle of Gettysburg, delayed by the failure to receive until now the reports of several corps and division commanders, who were severely wounded in the battle. On June 28, I received the orders of the President of the United States placing me in command of the Army of the Potomac. The situation of affairs at that time was briefly as follows: The Confederate army, commanded by General R. E. Lee, estimated at over 100, 000 strong, of all arms, had crossed the Potomac River and advanced up the Cumberland Valley. Reliable intelligence placed his advance {Ewell's corps
on the Susquehanna, at Harrisburg and Columbia; Longstreet's corps at Chambersburg, and Hill's corps between that place and Cashtown. My own army, of which the most recent return showed an aggregate of a little over 100, 000 was situated in and around Frederick, Md., extending from Harper's Ferry to the mouth of the Monocacy, and from Middletown to Frederick. June 28 was spent in ascertaining the position and strength of the different corps of the army, but principally in bringing up the cavalry, which had been covering the rear of the army in its passage over the Potomac, and to which a large increase had just been made from the forces previously attached to the Defenses of Washington. Orders were given on that day to Major-General French, commanding at Harper's Ferry, to move with 7, 000 men of his command to occupy Frederick and the line of the Baltimore and Ohio Railroad, and, with the balance of his force, estimated at 4. 000, to remove and escort the public property to Washington. On the 20th, the army was put in motion, and on the evening of that day was in position, the left at Emmitsburg and the right at New Windsor. Buford's division of cavalry was on the left flank, with the advance at Gettysburg. Kilpatrick's division was in the front at Hanover, where he encountered this day General Stuart's Confederate cavalry, which had crossed the Potomac at Seneca Creek, and, passing our right flank, was making its way toward Carlisle, having escaped Gregg's division, delayed in taking position on the right flank by the occupation of the roads by columns of infantry. On the 30th, the right flank of the army was moved up to Manchester, the left still being at Emmitsburg, in the vicinity of which place three corps {the First Eleventh, and Third
were collected, under the orders of Major-General Reynolds. General Buford having reported from Gettysburg the appearance of the enemy on the Cashtown road in some force, General Reynolds was directed to occupy Gettysburg. On reaching that place on July 1, General Reynolds found Buford's cavalry warmly engaged with the enemy, who had debouched his infantry through the mountains on the Cashtown road, but was being held in check in the most gallant manner by Buford's cavalry. Major-General Reynolds immediately moved around the town of Gettysburg, and advanced on the Cashtown road, and without a moment's hesitation deployed his advanced division and attacked the enemy, at the same time sending orders for the Eleventh Corps {General Howard
to advance as promptly as possible. Soon after making his dispositions for the attack, Major-General Reynolds fell, mortally