On Sunday morning, the 5th, I had an inspection of arms. At 4 p. m. marched with brigade in the direction of Frederick City; bivouacked at 8 p. m. at Two Taverns. During the 6th, we remained in bivouac. On the 7th, marched 9 1/2 miles to near Taneytown; received rations and bivouacked. On the 8th, marched at 5 a. m. Soon after moving a hard rain came on, making the roads very muddy. This was a hard day's march for the men; bivouacked for the night near Frederick City. July 9, marched at 5 a. m., Sixty-fourth leading the brigade; bivouacked near [Crampton's Gap], Md. On the 10th, moved at 5 a. m. ; crossed Antietam River at Keedysville; marched 3 1/2 miles, and formed a line of battle; at night bivouacked. On the 11th, reveille at 4 a. m. ; marched at 6 a. m. ; formed line of battle at 11 a. m. at Lapham's [Jones'] Cross-Roads; sent picket detail to brigade headquarters of 1 captain, 1 lieutenant, and 43 enlisted men. Remained here until the afternoon of the 12th, when we advanced with the brigade to a wood, where we formed line of battle on the crest of a rocky ledge, Sixty-fourth on the right. At dark, commenced throwing up entrenchments. On the 13th, we finished our breastworks. On the 14th, at 6 a. m. the brigade advanced toward Falling Waters. The Sixty-fourth were deployed as skirmishers, the left connecting with the right of the Fifth New Hampshire. We moved as skirmishers in this position several miles, when I was ordered to Colonel Brooke, who ordered me to march as support to line of skirmishers on the left of Lieutenant-Colonel Chapman, of the Fifty-seventh New York. I was afterward ordered to take charge of 164 enlisted men and 2 commissioned officers, taken prisoners by the skirmishers of the Fourth Brigade. The provost-marshal coming up, relieved me, when I reported to the brigade, which had halted in a ravine, where we bivouacked for the night. On the 15th, marched at 5 a. m., Sixty-fourth leading the brigade. Marched to nearly opposite Harper's Ferry, when we bivouacked by the side of the canal for the night. On the 16th, marched at 9 a. m. to Pleasant Valley, and bivouacked, and issued clothing to the men. On the 17th, remained at Pleasant Valley. The men, obeying the injunction of the brigade commander, bathed freely. On the 18th, marched at 6 a. m. Crossed the Potomac on pontoon bridge at Harper's Ferry. Marched south 7 miles, and bivouacked. At 11 a. m. on the 19th, marched 6 miles farther south, and bivouacked. On the 20th, marched at 8. 30 a. m. ; bivouacked near Bloomfield. On the 21st, did not move. Wednesday, July 22, marched at 2 p. m. and halted toward evening with the brigade, holding Ashby's Gap. On the 23d, at 2 p. m., left Ashby's Gap and marched about 8 miles toward Manassas Gap, when we halted at dusk and issued rations. Heard firing in the direction of Manassas Gap. Were soon ordered to pack up, and were very soon on our way with the brigade to Manassas Gap, which we entered and passed through, bivouacking at 1 a. m. of the 24th.