"...Between 5 and 6 p.m. the three regiments engaged (the 32nd Indiana, 15th Ohio, and 89th Illinois, which had been skirmishing for three hours - my note) had again nearly exhausted their ammunition. I ordered the Forty-ninth Ohio Volunteers to charge. The battle-field now presented a view not many favored to witness. The Forty-ninth Ohio Volunteers advanced in splendid style, through open woods, received the cheers of the rest of the brigade. The men of these regiments who had few rounds left, and many that had none, advanced bravely with the Forty-ninth Ohio. When coming under the enemy's fire, Colonel Gibson gave the order, "Advance firing." The regiment formed in four ranks. The first rank delivered their fire, the fourth, third, and second in secession took the front and delivered their fire, but already to the third volley the enemy did not answer. He had precipitately left his position. The Forty-ninth Ohio Volunteers took position at a fence, inclosing an open field. I judged it useless to charge over open ground, exposed to the enemy's canister, and unable to follow him as quick as he ran."
"...The prompt advance of the Fifteenth Ohio Volunteers and the splendid and irresistible charge of the Forty-ninth Ohio Volunteers are military deeds worthy to be registered in the annals of the nation."
The portion of Colonel Gibson's report (dated June 30, 1863) dealing with advance fire reads as follows:
"...At about 5 p.m. our lines were attacked in force, and we were ordered forward to relieve the Thirty-second Indiana, then nearly out of ammunition. Advancing rapidly to the base of a wooded hill in the rear of the Thirty-second, the regiment wheeled into line, and moved to the front in splendid order, in the face of fire from musketry and artillery."
"...In consulting the general commanding the brigade as to the best mode of attacking the enemy, he directed me to try our drill, recently originated and introduced to the brigade, for firing, "on the advance." It was a complete success, and I claim that it was first used in actual battle. As we advanced, our front was on a ridge in the open woods. Twenty rods from the woods, in front of our right and 5 rods in front of the woods in front of our left, was a low rail fence. Beyond this was a corn-field, stretching off 400 yards to the front of the fence was a narrow gully. While our right was covered by some small farm buildings and an orchard, the enemy moving down the road under cover of his artillery, had organized a strong line in this gully, and behind the orchard and buildings. At the command, "Advance firing," the regiment, though under fire, formed in four ranks as promptly as if on drill, and opened a terrific fire, advancing rapidly through the woods to the rail fence, the right wheeling into position. The enemy was driven from his concealment and compelled to retreat before our fire, which was delivered with a regularity and rapidity that no veteran could withstand. Withdrawing by his left flank, under cover of the buildings, the enemy rallied on the wooded hill beyond the corn-field. Having thus driven back the enemy, we remained in position at the fence until the arrival of Miller's brigade, which relieved us, and we retired from the field harassed only by the enemy's artillery."
From: Official Records, Series I, Vol. 23, Part 1 pp. 496-49