every reason to fear a vigorous pursuit from the enemy's fresh troops, I was desirous of forming a strong rear guard, but neither the efforts of the officers of the Regular Army nor the coolness of the regular troops with me could induce them to form a single company. We relied entirely for our protection on one section of artillery and a few companies of cavalry. Most of the road was favorable for infantry, but unfavorable for cavalry and artillery.

About dusk, as we approached the Warrenton turnpike, we heard a firing of rifled cannon on our right, and learned that the enemy had established a battery enfilading the road. Captain Arnold, with his section of artillery, attempted to run the gauntlet, and reached the bridge over Cub Run about two miles from Centreville, but found it obstructed with broken vehicles, and was completed to abandon his pieces, as they were under the fire of those rifled cannon. The cavalry turned to the left, and after passing through a strip of woods and some fields, struck a road which led them to some camps occupied by our troops in the morning, through which we regained the turnpike. About 8 p.m. we reached the camp we had occupied in the morning. Had a brigade from the reserve advanced a short distance beyond Cub Run near one-third of the artillery lost might have been saved, as it was abandoned at or near this crossing.

Such a rout I never witnessed before. No efforts could induce a single regiment to form after the retreat was commenced. Our artillery was served admirably, and did much execution. Some of the volunteer regiments behaved very well, and much excuse can be made for those who fled, as few of the enemy could at any time be seen. Raw troops cannot be expected to stand long against an unseen enemy. I have been unable to obtain any report from the zouaves, as Colonel Farnham was wounded, and is sick in the hospital. I have only the list of the killed and wounded. Since the retreat more than three-fourts of the zouaves have disappeared. The brigade and regimental reports, with the lists of the killed and wounded, are inclosed herewith.

I beg leave to express my obligations to the officers of my staff, viz: Captain Horatio G. Wright, Lieutenant G. W. Snyder, and Lieutenant Francis U. Farquhar, of the Engineers; Captain Chauncey McKeever, assistant adjutant-general; Lieutenant John J. Sweet, Second Cavalry,and Lieutenant John D. Fairbanks, First Michigan Regiment, for the able and fearless manner in which they performed their duties, and to recommend them to your favorable consideration.

I have the honor to be, sir, very respectfully, your obedient servant,

S. P. HEINTZELMAN,

Colonel Seventeenth Infantry, Commanding Division.

Captain JAS. B. FRY,

Assistant Adjutant-General, U. S. Army, Arlington, Va.