We found no difficulty in crossing over, and met with no opposition in ascending the steep bluff opposite with our infantry, but it was impassable to the artillery, and I sent word back to Captain Ayres to follow if possible, otherwise to use his discretion.  Captain Ayres did not cross Bull Run, but remained on that side, with the rest of your division.  His report herewith describes his operations during the remainder of the day.  Advancing slowly and cautiously with the head of the column, to give time for the regiments in succession to close up their ranks, we first encountered a party of the enemy retreating along a cluster of pines; Lieutenant-Colonel Haggerty, of the Sixty-ninth, without orders, rode out alone, and endeavored to intercept their retreat.  One of the enemy, in full view, at short range, shot Haggerty, and he fell dead from his horse.  The Sixty-ninth opened fire on this party, which was returned; but, determined to effect our junction with Hunter’s division, I ordered this fire to cease, and we proceeded with caution toward the field where we then plainly saw our forces engaged.  Displaying our colors conspicuously at the head of our column, we succeeded in attracting the attention of our friends, and soon formed the brigade in rear of Colonel Porter’s.  Here I learned that Colonel Hunter was disabled by a severe wound, and that General McDowell was on the field.  I sought him out, and received his orders to join in pursuit of the enemy, who was falling back to the left of the road by which the army had approached from Sudley Springs.  Placing Colonel Quinby’s regiment of rifles in front, in column, by division, I directed the other regiments to follow in line of battle, in the order of the Wisconsin Second, New York Seventy-ninth, and New York Sixty-ninth.  Quinby’s regiment advanced steadily down the hill and up the ridge, from which he opened fire upon the enemy, who had made another stand on ground very favorable to him, and the regiment continued advancing as the enemy gave way, till the head of the column reached the point near which Rickett’s battery was so severely cut up.  The other regiments descended the hill in line of battle, under a severe cannonade; and, the ground affording comparative shelter from the enemy’s artillery, they changed direction, by the right flank, and followed the road before mentioned.  At the point where this road crosses the ridge to our left front, the ground was swept by a most severe fire of artillery, rifles, and musketry, and we saw, in succession, several regiments driven from it; among them the Zouaves and battalion of marines.  Before reaching the crest of this hill, the roadway was worn deep enough to afford shelter, and I kept the several regiments in it as long as possible; but when the Wisconsin Second was abreast of the enemy, by order of Major Wadsworth, of General McDowell’s staff, I ordered it to leave the roadway, by the left flank, and to attack the enemy.