July 1, 1861 - On the 16th day of July the campaign opened with us. The division marched to Annandale, bivouacked for the night, resumed the march on the following morning, passed through Fairfax, which had been evacuated on the approach of the Union army, from thence to a point north of Centreville, where the division remained until the 21st. At 3 A.M. the troops moved out of camp. To fully describe the scene at that hour, a poet's brain and pencil were needed. The moon never shone more brightly, and as each regiment filed out of it's camp towards the column already en route on the pike, the moon's rays, reflected from thousands of bayonets and polished barrels, resembles a phosphorescent sea, whose brilliancy the fortunate beholder can never forget, and only faintly describe. As part of Hunter's flanking column, Porter's brigade, passed down the Warrenton pike to a point beyond Cub Run, bore off to the right, and crossed Bull Run at Sudley's ford, went into action and unintermittingly , fought for four hours and a half; was at length forced to retire, the enemy being reinforced by the arrival of fresh troops under Johnson. Three times during the engagement the regiment occupied that spot opposite the "Henry" house, its character fitly described in its name, "slaughter pen." On gaining that position for the third, it re-captured the guns of Rickett's battery, but for lack of support was obliged to abandon them. The conduct of the regiment during the day was of such a character as to have won the praise of the commanding general, and special mention in general orders.

The loss of the regiment was as follows:

During the early part of the engagement Colonel Wood was wounded and taken prisoner, afterwards sent to Richmond, held with others as hostages for privateers captured by United States steamer San Jacinto. On his release was discharged from service, his wound unfitting him for field service.

July 22d, 1861 - The regiment returned with the retreating column, and went into the old camp at Arlington, reaching that point on the 22d instant. Shortly after our return to camp, the engineer corps being in excess of a regular organization, was discharged the service.

Sept. 28th 1861 - Remained in this camp until September 28th , when the regiment , under command of Lieutenat-Colonel E. B. Fowler, participated in the advance of the army upon Munson's and Hall's Hills. The enemy, falling back with only a show of resistance, these positions were occupied, and the regiment and brigade, the latter under command of General E. D. Keyes, went into winter quarters on Upton's Hill, and remained there until the spring of 1862.

The duties of the regiment during the winter were of no light character. Besides the daily routine of drills (regimental and brigade) it performed unusually severe picket duty, which, by the way, was a branch of duty not so thoroughly systemized as at a later date, when the task came at longer intervals and was borne impartially by all the troops on the immediate front, including the cavalry force, which at this time was not used.

Nov. 18th, 1861 - On the 18th Nov., while the regiment was on picket, covering the front near Fall's church, the outposts were suddenly attacked by Stuart's First Virginia cavalry, under command of Fitzhugh Lee, numbering about 500 men ; despite the courage and determined resistance of the company occupying the post, it was driven in, the enemy only retiring upon the approach of the reserve.

The loss in this encounter was two killed, three wounded, ten prisoners ; the latter including one officer - Lient. Grummen.