Bridge, on the road to Gainesville, with directions to take possession of the bridge, and thereby open the road to Gainesville. The brigade of Brigadier-General Milroy advanced rapidly toward the bridge, and drove the enemy, who was stationed there with some cavalry and artillery, back toward Gainesville, while the pioneers repaired the bridge, which had been set on fire and partially destroyed by the enemy. In a short time the whole of General Milroy's brigade had passed the river and pressed forward against Gainesville, making on their way about 150 prisoners. I now ordered General Schurz to pass the river and follow General Milroy and to take position behind him. The division of General Schenck also crossed the river, and the infantry brigade of General Steinwehr remained in reserve at the bridge. Such was the position of the First Corps on the evening of the 27th.

During the night General McDowell's corps arrived at Buckland Mills, and I received orders at 3 o'clock in the morning to march to Manassas and to take position, with my right resting on the railroad leading from Warrenton Junction to Manassas Junction; so, at least, I understood the order.

On this march our cavalry, sent out to the left in the direction of Groveton, was shelled by the enemy, about 1 1/2 miles distant from the road on which we marched; and, besides this, an artillery engagement began between the corps of General McDowell and the enemy. I immediately halted, ordered the whole corps to counter-march, and formed in order of battle on the heights parallel with the Centerville-Gainesville road. The enemy's infantry and cavalry pickets were about 300 yards from our line, and our skirmishers had already advanced against them when, on a report made to General McDowell, I received orders to march forthwith to Manassas Junction. I reluctantly obeyed this order, marched off from the right, and was within 2 1/2 miles from Manassas, when our cavalry reported that Manassas was evacuated by the enemy, and that General Kearny was in possession of that point. As I was sure that the enemy must be somewhere Centerville and Gainesville, I asked permission to march to New Market, whereupon I was directed to march to Centerville. This order was in execution, and the troops prepared to cross the fords of Bull Run, when our advance met the enemy on the road leading from New Market to Groveton and Sudley's Ford, this side of Bull Run. About the same time I received a report from General Pope that the enemy was concentrating at Centerville. Supposing that this was correct, I directed the brigades of General Milroy and Colonel McLean to advance against the enemy this side of Bull Run, on the road to Sudley Springs, and left General Stahel' brigade and General Schurz' division near the fords, the latter division facing toward Centerville.

As soon, however, as I had ascertained that Centerville was evacuated by the enemy I followed with these troops to assist Brigadier-General Milroy and Colonel McLean, who, under the direction of Brigadier-General Schenck, were briskly engaged with the left of the enemy's forces, whose right had engaged a brigade of the Third Corps. Our artillery advanced steadily until the darkness of night interrupted their movements. They encamped for the night near Mrs. Henry's farm, one regiment taking position on the Centerville-Gainesville turnpike, the main force fronting toward Sudley Springs and Groveton.

2.-BATTLE OF GROVETON, NEAR BULL RUN, ON FRIDAY, AUGUST 29, 1862.

On Thursday night, August 28, when the First Corps was encamped