As the day wound down, in response to Major General John Pope's orders, Union Brigadier General Rufus King's Division marched east down the Warrenton Turnpike near the small village of Groveton. The Union high command had charged them with finding the elusive Confederate General Thomas J. Jackson and his men. Positioned nearly parallel to the turnpike and hidden within the distant tree line at the top of a gradual rise, General Jackson turned to his commanders and ordered the attack saying simply, "Bring out your men Gentlemen." The Southern artillery responded, opening fire on the passing blue lines. Called forward by Union General John Gibbon to stem the threat, the 2nd Wisconsin and then the rest of his command faced at about 80 yards the veteran troops of General Jackson's Stonewall Brigade. The group of Union men soon to be known as the Iron Brigade would begin to prove their mettle as soldiers against Jackson's stalwart Virginians.

General Gibbon would report of the beginning hostilities and his surprise at encountering their much sought after foe in this place. "I had no information of the presence of an infantry force in that position, which was occupied by General Hatch in person not three-fourths of an hour before. I therefore supposed that this was one of the enemy's cavalry batteries, and ordered the Second Wisconsin to face to the left and march obliquely to the rear against these pieces to take them in flank. As it rose an intervening hill it was opened upon by some infantry on its right flank. The left wing was thrown forward to bring the regiment facing the enemy, and the musket firing became very warm. The Nineteenth Indiana was now ordered up in support and formed on the left of the Second Wisconsin, whilst the Seventh Wisconsin was directed to hold itself in reserve. As the enemy appeared to be now heavily re-enforced, the Sixth and Seventh Wisconsin were both ordered into line, and I sent repeated and earnest requests to division headquarters for assistance."

For almost two hours, Confederate and Union forces fired into each others' lines with men falling at every turn. When darkness descended, a fearful percentage were casualties on this first day of what would become the Battle of Second Manassas. Again, General Gibbon would state of his brigade's sacrifice, "Of the conduct of my brigade it is only necessary for me to state that it nobly maintained its position against heavy odds. The fearful list of killed and wounded tells the rest. The troops fought most of the time not more than 75 yards apart.

The total loss of the brigade is, killed, 133; wounded, 539; missing, 79. Total, 751, or considerably over one-third the command."

General Jackson would also describe the escalating conflagration in his official report. "My command had hardly concentrated north of the turnpike before the enemy's advance reached the vicinity of Groveton from the direction of Warrenton. General Stuart kept me advised of the general movements of the enemy, while Colonel Rosser, of the cavalry, with his command, and Colonel Bradley T. Johnson, commanding Campbell's brigade, remained in front of the Federals and operated against their advance. Dispositions were promptly made to attack the enemy, based upon the idea that he would continue to press forward upon the turnpike toward Alexandria; but as he did not appear to advance in force, and there was reason to believe that his main body was leaving the road and inclining toward Manassas Junction, my command was advanced through the woods, leaving Groveton on the left, until it reached a commanding position near Brawner's house. By this time it was sunset; but as his column appeared to be moving by, with its flank exposed, I determined to attack at once, which was vigorously done by the division of Taliaferro and Ewell. The batteries of Wooding, Poague, and Carpenter were placed in position in front of Starke's brigade and above the village of Groveton, and, firing over the heads of our skirmishers, poured a heavy fire of shot and shell upon the enemy. This was responded to by a very heavy fire from the enemy, forcing our batteries to select another position. By this time Taliaferro's command, with Lawton's and Trimble's brigades on his left, was advanced from the woods to the open field, and was now moving in gallant style until it reached an orchard on the right of our line and was less that 100 yards from a large force of the enemy. the conflict here was fierce and sanguinary. Although largely re-enforced, the Federals did not attempt to advance, but maintained their ground with obstinate determination.

Both line stood exposed to the discharges of musketry and artillery until about 9 o'clock, when the enemy slowly fell back, yielding the field to our troops." [5]