On Wednesday, July 15, left bivouac near Williamsport at 6. 15 a. m., and marched to Sharpsburg, passing through the town at noon, and going into bivouac at 1 p. m. On Thursday, July 16, left bivouac at 6 a. m., and marched by way of Brownsville to near Maryland Heights, encamping at 2 p. m. At 4. 30 p. m. on Friday, July 17, marched to Harper's Ferry, crossing the river on pontoons. Pushed on 5 miles farther, and went into bivouac at 8 p. m. On Saturday, July 18, marched at 3 a. m. to Hillsborough, and halted at noon for the night. On Sunday, July 19, marched to Woodgrove. On Monday, July 20, left at 4. 30 a. m., and marched to Upperville, at which place I was directed to be prepared at any moment to meet the enemy. On Tuesday, July 21, marched to Piedmont, and bivouacked at 5. 30 p. m. On Thursday, July 23, in accordance with orders from Brigadier-General Prince, I broke camp at Piedmont at 4. 30 a. m., marched to Manassas Gap, 9 miles distant, and halted for two hours. I was then ordered to the front, and at the same time notified that the enemy was advancing in force. Reaching the rear of the First Division, I was directed to form in column of battalions, closed in mass, to support the division in my front; also to send out one regiment to support the left of the line of skirmishers, and one regiment to support Winslow's battery. For these duties I detailed the First Massachusetts Volunteers, Lieutenant-Colonel Baldwin commanding, and the Twenty-sixth Pennsylvania Volunteers, Major Bodine commanding. During the course of the afternoon, I assumed several positions by direction of the brigadier-general commanding the division, but did not become engaged. At 7 o'clock on the morning of Friday, July 24, I was ordered to move my command in the rear of the Third Brigade of this division, in the direction of Front Royal. When within a mile of that place, I formed line of battle on the right of the Third Brigade, throwing out skirmishers to the front, with two regiments to support them. This position I sustained for one hour without advancing. The enemy opened fire from one of his guns, but without doing any injury whatever. I then advanced over a lofty hill thickly studded with undergrowth, and through Front Royal, halting on the west side for one hour, when I took up the line of march in the direction of the Gap, reaching Markham at dusk, having marched about 20 miles. At 4 a. m. on Saturday, July 25, I marched 3 miles to Piedmmont, halting near that place until 12 m., at which hour, by direction of Brigadier-General Prince, I proceeded with my command 3 miles beyond Salem, going into bivouac on the Warrenton road at 5. 30 p. m. On Sunday, July 26, left camp at 5. 25 a. m., and marched to and through the town of Warrenton, and formed camp 3 miles beyond. During these operations but one casualty occurred in my command, viz, Private Thomas Richards, Company C, Eighty-fourth Pennsylvania Volunteers, wounded in leg by musket-ball.

I have the honor to remain, your most obedient servant,

JOS. B. CARR,

Brigadier-General.

Major CHARLES HAMLIN, Asst. Adjt. General, Second Division, Third Corps.