Here's the portion of the report of Shiloh by Chalmers which describes the encounter with the 54th Ohio and 55th Illinois (the 71st Ohio of Stuart's Brigade broke and ran at first contact).

Moving by the right flank, we filed to the right, directly south, until we recrossed the ravine behind us, and when we reached the summit of the opposite hill we moved in a southeast direction until our right rested upon the edge of Lick Creek bottom. Here again we were ordered to rest, which we did for some half hour, when we again started forward. A few skirmishers of the enemy, having secretly advanced close to our left, fired upon the Fifty-second Tennessee Regiment, which broke and fled in most shameful confusion. After repeated efforts to rally it this regiment was ordered out of the lines, where it remained during the balance of the engagement, with the exception of two companies, Capts. J. A. Russell and A. N. Wilson, who, with their commands, fought gallantly in the ranks of the Fifth Mississippi Regiment.

When the orders were received from General Withers to move on, skirmishers were thrown out in front of the whole line, and placed in command of Maj. F. E. Whitfield, of the Ninth Mississippi Regiment, who led them with great coolness and with marked ability and skill. Our orders were to swing around, with our right resting on the creek bottom, and to drive the enemy before us toward Pittsburg, and we accordingly moved forward, advancing most rapidly on the right and gradually wheeling the whole line. In this order we were marching when our skirmishers developed the enemy concealed behind a fence, in thick undergrowth, with an open field or orchard in his front. The width of this orchard was about 350 or 400 yards, and behind it was a very steep and perfectly abrupt hill, at the foot of which ran a small branch. At the base of this hill ran the Hamburg and Pittsburg road, skirting the orchard at its base and then turning to the right running alongside of it, the orchard being to the right of the road. The ground from the branch to the fence, where the enemy was concealed, was a gradual ascent, and our line was in full view of the enemy from the time it crossed the stream. The Ninth Mississippi was now on the left, and there was a space of about 30 yards between its left and the Hamburg and Pittsburg road. As soon as I discovered the position of the enemy I ordered up Gage's battery, which until now had not been engaged, and put it in position on the hill above the branch.

My line moved on across the orchard in most perfect order and splendid style, and to my great surprise not a shot was fired until we came within about 40 yards of the fence, then a heavy fire was opened on us in front, and at the same time a column was seen coming at double-quick down the Hamburg and Pittsburg road, with the evident intention of getting in our rear and cutting off the whole brigade. As soon as this column was fairly in sight, coming over the opposite hill, Gage's battery opened a well-directed fire on its head, and it was scattered in confusion, and at the same moment our infantry made a charge in front, and after a hard fight drove the enemy from his concealment, though we suffered heavily in killed and wounded.

After this fight our ammunition was exhausted, and, the wagons being some distance behind, we lost some time before it was replenished. As soon, however, as the ammunition could be distributed we moved on, with the right resting on the edge of the Tennessee River bottom, with the same orders as before.

When we had gone about a quarter of a mile we again encountered the enemy in a strong position on a hill with a deep ravine in his front, and a very stubborn fight ensued, in which we lost many gallant men, among them the Rev. M. L. Weller, chaplain of the Ninth Mississippi Regiment, a pure man and ardent patriot and a true Christian, and Capts. R. J. Armstrong and T. C. K. Bostick, of the Fifth Mississippi Regiment, who fell gallantly leading on their respective companies.

Here again Gage's battery did good service, though it was some time before it could be brought into position, owing to the rough nature of the ground and the want of roads, and I here take occasion to say that I cannot speak too highly of the energy, skill, and labor displayed by the men of this battery throughout the day in cutting their way through a thickly-wooded country over ravines and hills almost impassable to ordinary wagons.

After about an hour's hard fighting the enemy again retreated, learning many of his dead on the field.

Here is Col. David Stuart's report of the same action from a Federal perspective --

The brigade, composed of the Fifty-fifth Illinois, commanded by Lieutenant-Colonel Malmborg; the Fifty-fourth Ohio, Col. T. Kilby Smith, and the Seventy-first Ohio, Col. R. Mason, occupied the extreme left of the advance, General Prentiss' division on my right and front. In obedience to General Sherman's orders I kept a company at and in the vicinity of the ford of Lick Creek, on the Hamburg road, and another on and in the vicinity of the Bark road (coming in on the hills opposite and southeast of the encampment), as picket guards, and on his order on Saturday sent six companies out on the Hamburg road, with a squadron of cavalry sent forward by General McClernand, to reconnoiter beyond Hamburg. The disposition of my pickets was reported to and approved by General Sherman. At 7.30 o'clock on Sunday morning I revived a verbal message from General Prentiss that the enemy were in his front in force. Soon after my pickets sent in word that a force, with artillery, were advancing on the Back road. In a very short time I discovered the Pelican flag advancing in the rear of General Prentiss' headquarters. I dispatched my adjutant (Looms), of the Fifty-fourth Ohio, to General Hurlbut, who occupied with his division the rear in the center, to inform him that General Prentiss' left was turned, and to ask him to advance his forces. The reply was that he would advance immediately. Within fifteen minutes General Hurlbut sent forward a battery, which took position on the road immediately by Colonel Mason's (Seventy-first) headquarters. A regiment (the Forty-first Illinois, as I remember) formed in line on the right of this battery. Observing these dispositions, and expecting that the remainder of General Hurlbut's division would be up quickly, I established my line of battle accordingly, with the right of the Seventy-first Ohio resting opposite the eastern extremity of the camp of the Fifty-fifth Illinois, the Fifty-fifth Regiment next, on the left, and the Fifty-fourth beyond, facing the south. I had two companies of the Fifty-fifth Illinois and two companies of the Fifty-fourth Ohio detached as skirmishers on the hills opposite and across the creek or ravine where the enemy was endeavoring to plant a battery, covered by a much larger force of skirmishers. From a convenient position on the brow of the bank north of the creek with my glass I could observe all their movements. Having succeeded in planting their battery in a commanding position they opened a fire of shell upon us, under cover of which the infantry advanced upon us diagonally from the left of Prentiss’ division, and also from the right of their battery. I hastened in person to the battery I had left half an hour before in front of Colonel Mason's tent to order them farther to the east, in front of my headquarters, where they would have had a splendid fire as well upon the enemy's battery as upon the advancing infantry. The battery had left without firing a gun and the battalion on its right had disappeared.

For above a quarter of a mile to my right no soldier could be seen, unless fugitives, making their way to the rear. A large body of the enemy's troops were advancing due north toward Mason's camp, and I saw that the position of my brigade was inevitably flanked by an overwhelming and unopposed force. Hastening back to my brigade, I found the enemy rapidly advancing on its front. The Seventy-first Ohio had fallen back, under the shelling of the enemy's guns, to some position (as I am informed by Colonel Mason) about 150 yards in the rear, and reformed on a ridge of ground very defensible for infantry, but I could not find them, and had no intimation as to where they had gone. Before I could change position the Fifty-fifth Illinois and Fifty-fourth Ohio were engaged, but as soon as possible I withdrew them to a position on the brow of a hill, and formed a line which, extended, would intersect my first line diagonally from northwest to southeast. At this point I had not to exceed 800 men of the Fifty-fifth Illinois and Fifty-fourth Ohio. I saw nothing more of the Seventy-first Regiment through the fight. The enemy's force of five regiments of infantry and a battery of four guns, which had been moving on our right flank, were here brought to a stand, and formed a line of battle; a body of cavalry were sent off on our then right toward our rear, to harass or cut off our retreat; a part of the force which had attacked our first front was disposed with a view of flanking us on our present left. Against this latter force (moving through a ravine, which had its mouth just below and in the rear of our extreme left) I sent a detachment of four companies of Zouaves, Fifty-fourth Ohio, under Major Fisher, by whom they were held in check during the fight. This engagement opened, the enemy s line and ours being established at a distance of about 150 yards apart. At this point we fought, and held them for upwards of two hours. The enemy's lines were within the edge of a grove, pretty well defended by trees; the space between us was an open, level, and smooth field. The disposition of their forces was made deliberately, and occupied fully fifteen minutes after we came upon the ground.

Inadequate as I knew my force to be, I was encouraged to fight it and hold my position, first with the object of detaining the enemy's forces from advancing toward the river, and secondly because I received a message from General McArthur, who appeared in person somewhere in my vicinity, to hold my position, and that he would support me on my right. I could not find the Seventy-first Ohio Regiment, and had less than 800 men under my command. During the action we observed a battery planted southeast of us, in a commanding position, to enfilade our line. It was, however, employed with little beyond threatening effect, the firing being too high. We had received no support on our right, as promised by General McArthur. We had emptied the cartridge boxes of the killed and wounded, and our ammunition was exhausted. Our fire was so slackened from this cause and our losses that I was apprehensive of a forward movement by the enemy, who could easily have overwhelmed us and thrown us into ruinous confusion. With the advice of Colonel Smith, of the Fifty-fourth Ohio, and Lieutenant-Colonel Malmborg, commanding the Fifty-fifth Illinois. I gave the order to fall back through the ravine and reform on a hill to our right. I led the remnant of my brigade in good order to the point selected. When we reached it, the enemy had advanced on our left with their battery and were on a commanding position within 600 yards. They opened a fire of shell upon us, which compelled me to move on still farther, sheltering the command as well as possible by ravines and circuitous paths, till we reached a cavalry camp, where the brigade was reformed.