Numbers 26. Report of Brigadier General Martin D. Hardin, U. S. Army, commanding division of Twenty-second Army Corps, of the defense of Washington.

HEADQUARTERS HARDIN'S DIVISION,
July 19, 1864.

SIR: I have the honor to make the following report of the operations of my command on the 10th, 11th, 12th, 13th, and 14th instant:

On the night of the 10th I was ordered to make my headquarters at Tennallytown. I learned before leaving the city the Major-General McCook was to command a reserve force to be stationed at Crystal Spring. I left the city about 11 p. m. The last report from Major Fry, commanding the cavalry on the Rockville road being that he was falling back and would make a stand just outside of Tennallytown, the enemy pushing him back rapidly. Upon arriving at Fort Reno, headquarters First Brigade, Colonel Warner commanding, I felt assured there was not so evident danger to the defenses as I was led to suppose from the cavalry reports. Everything was very quiet. Colonel Warner had made good dispositions of his troops, and the Veteran Reserves were coming up rapidly. Colonel Gile, with First Brigade of Veteran Reserves reported about midnight.

Colonel Lowell, Second Massachusetts Cavalry, having moved out at daylight Monday morning, in command of all the available cavalry, commenced skirmishing. About 6.30 a. m. the enemy's advance fell back several miles to their reserves, when they began forcing Colonel Lowell's command back. The enemy occasionally fired a small rifled gun near the road. Colonel Lowell remained on infantry picket-line. Cavalry scouts were sent out the River and Aqueduct roads. No enemy reported in that direction. Heavy clouds of dust and occasionally troops and wagons were seen from signal station at Fort Reno, moving apparently from Rockville in direction of Seventh-street pike. General McCook was notified, the skirmish line strengthened from Fort Reno to Rock Creek, and a proper disposition of the infantry supports made. Skirmishing was quite brisk on the right near Rock Creek until dark.

During the night of the 11th the pickets were very much strengthened from Brookeville road to Rock Creek. One company of Veteran Reserves, under Captain Clark, Sixth Regiment Veteran Reserve Corps, made a gallant effort to take a barn which the enemy were using to advantage against our skirmishers in front of Fort De Russy. Captain Clark was slightly wounded and many of his company were wounded. These very efforts and the determined way of holding the picket-line showed the enemy that he would have to make a desperate assault to carry this portion of the line, which I believe one of the weakest points of the Sixth Corps skirmishers it is considered made the enemy think we were prepared for an assault.

I respectfully call attention to the reports of the brigade commanders appended. Such telegrams as are in my reach are appended. Many, I think were carried off by the operators. My adjutant-general had to remain in the city. I sent my inspector-general, Captain Markle, to the Second Brigade. There did not appear to be sufficient attention paid to pickets on that front. He was put there to