The 6th Wisconsin mustered into the United States Army in the early months of 1861. Most companies were gathered in sometime between April and June. These men came from all parts of southern Wisconsin. Some companies were from Fon du Lac area, Captain Rufus Dawes’ (commander of the 6th at Gettysburg) company arrived from Mauston, with two companies comprised of Italians and Germans from Milwaukee. After mustering, they were shipped off to Washington D.C. and drilled day after day for about a year.

Their first action came two days before the Second Battle of Bull Run in August of 1862 in the Brawner farm fields near Gainsville, Virginia. Here they ran into portions of Stonewall Jackson's corps. Despite being greatly outnumbered, they were able to hold off Stonewall and his men for a few hours until darkness ended the contest. This is where the Iron Brigade first began to earn its reputation. Captured Confederates would refer to them as the “Black Hat Devils of the Army of the Potomac.” Others prisoners were heard to say, “…it's no use to fight that Big Hat Brigade, we will only get cut to pieces.” Already in their first fight, they had earned the fear and respect of their enemies.

And what if that invasion should be successful, and in the coming battle, the Army of the Potomac should be overpowered? Would it not be?

When our army was much larger than at present-had rested all winter-and, nearly perfect in all its departments and arrangements, was the most splendid army this continent ever saw, only a part of the Rebel force, which it now had to contend with, had defeated it -its leader, rather- at Chancellorsville!

Now the Rebel had his whole force assembled, he was flushed with recent victory, was arrogant in his career of unopposed invasion, at a favorable season of the year. His daring plans, made by no unskilled head, to transfer the war from his own to his enemies' ground, were being successful. He had gone a day's march from his front before Hooker moved, or was aware of his departure. Then, I believe, the army in general, both officers and men, had no confidence in Hooker, in either his honesty or ability.

Did they not charge him, personally, with the defeat at Chancellorsville? Were they not still burning with indignation against him for that disgrace? And now, again under his leadership, they were marching against the enemy! And they knew of nothing, short of the providence of God, that could, or would, remove him. For many reasons, during the marches prior to the battle, we were anxious, and at times heavy at heart.

But the Army of the Potomac was no band of school girls. They were not the men likely to be crushed or utterly discouraged by any new circumstances in which they might find themselves placed. They had lost some battles, they had gained some. They knew what defeat was, and what was victory. But here is the greatest praise that I can bestow upon them, or upon any army: With the elation of victory, or the depression of defeat, amidst the hardest toils of the campaign, under unwelcome leadership, at all times, and under all circumstances, they were a reliable army still. The Army of the Potomac would do as it was told, always....

The Rebel infantry consisted of three Army Corps, each consisting of three Divisions, Longstreet, Ewell - the same whose leg Gibbon's shell knocked off at Gainesville on the 28th of August last year - and A. P. Hill, each in the Rebel service having the rank of Lieutenant General, were the commanders of these Corps. Longstreet's Division commanders were Hood, McLaws and Pickett; Ewell's were Rhodes, Early and Johnson, and Hill's were Pender, Heth and Anderson. Stewart and Fitzhugh Lee commanded Divisions of the Rebel cavalry. The rank of these Divisions’ commands, I believe, was that of Major General.

The Rebels had about as much artillery as we did; but we never have thought much of this arm in the hands of our adversaries. They have courage enough, but not the skill to handle it well. They generally fire far too high, and the ammunition is usually of a very inferior quality.

And, of late, we have begun to despise the enemies' cavalry too. It used to have enterprise and dash, but in the late cavalry contests ours have always been victor; and so now we think about all this chivalry is fit for is to steal a few of our mules occasionally, and their Negro drivers. This army of the rebel infantry, however, is good - to deny this is useless. I never had any desire to-and if one should count up, it would possibly be found that they have gained more victories over us, than we have over them, and they will now, doubtless, fight well, even desperately. And it is not horses or cannon that will determine the result of this confronting of the two armies, but the men with the muskets must do it - the infantry must do the sharp work....

As the Third Corps was the extreme left of our line, as it advanced, if the enemy was assembling to the West of Round Top with a view to turn our left, as we had heard, there would be nothing between the left flank of the Corps and the enemy, and the enemy would be square upon its flank by the time it had attained the road.

So when this advance line came near the Emmetsburg road, and we saw the squadrons of cavalry mentioned, come dashing back from their position as flankers, and the smoke of some guns, and we heard the reports away to Sickles' left, anxiety became an element in our interest in these movements.

The enemy opened slowly at first, and from long range; but he was square upon Sickles' left flank. General Caldwell was ordered at once to put his Division-the 1st of the Second Corps, as mentioned-in motion, and to take post in the woods at the left slope of Round Top, in such a manner as to resist the enemy should he attempt to come around Sickles' left and gain his rear. The Division moved as ordered, and disappeared from view in the woods, towards the point indicated at between two and three o'clock P.M., and the reserve brigade - the First, Col. Heath temporarily commanding - of the Second Division, was therefore moved up and occupied the position vacated by the Third Division.

About the same time the Fifth Corps could be seen marching by the flank from its position on the Baltimore Pike, and in the opening of the woods heading for the same locality where the 1st Division of the Second Corps had gone. The Sixth Corps had now come up and was halted upon the Baltimore Pike. So the plot thickened.

As the enemy opened upon Sickles with his batteries, some five or six in all, I suppose, firing slowly, Sickles with as many replied, and with much more spirit. The artillery fire became quite animated, soon; but the enemy was forced to withdraw his guns father and farther away, and ours advanced upon him. It was not long before the cannonade ceased altogether, the enemy having retired out of range, and Sickles, having temporarily halted his command, pending this, moved forward again to the position he desired, or nearly that. It was now about five o'clock, and we shall soon see what Sickles gained by his move.

First we hear more artillery firing upon Sickles' left-the enemy seems to be opening again, and as we watch the Rebel batteries seem to be advancing there. The cannonade is soon opened again, and with great spirit upon both sides. The enemy's batteries press those of Sickles, and pound the shot upon them, and this time they in turn begin to retire to position nearer the infantry.

The enemy seems to be fearfully in earnest this time. And what is more ominous than the thunder or the shot of his advancing guns, this time, in the intervals between his batteries, far to Sickles' left, appear the long lines and the columns of the Rebel infantry, now unmistakably moving out to the attack.

The position of the Third Corps becomes at once one of great peril, and it is probable that its commander by this time began to realize his true situation. All was astir now on our crest. Generals and their Staffs were galloping hither and thither-the men were all in their places, and you might have heard the rattle of ten thousand ramrods as they drove home and "thugged" upon the little globes and cones of lead.

As the enemy was advancing upon Sickles' flank, he commenced a change, or at least a partial one, of front, by swinging back his left and throwing forward his right, in order that his lines might be parallel to those of his adversary, his batteries meantime doing what they could to check the enemy's advance; but this movement was not completely executed before new Rebel batteries opened upon Sickles' right flank - his former front - and in the same quarter appeared the Rebel infantry also.

Now came the dreadful battle picture, of which we for a time could be but spectators. Upon the front and right flank of Sickles came sweeping the infantry of Longstreet and Hill. Hitherto there had been skirmishing and artillery practice - now the battle began; for amid the heavier smoke and larger tongues of flame of the batteries, now began to appear the countless flashes, and the long fiery sheets of the muskets, and the rattle of the volleys, mingled with the thunder of the guns. We see the long gray lines come sweeping down upon Sickles' front, and mix with the battle smoke; now the same colors emerge from the bushes and orchards upon his right, and envelope his flank in the confusion of the conflict.

O, the din and the roar, and these thirty thousand Rebel wolf cries! What a hell is there down that valley!

These ten or twelve thousand men of the Third Corps fight well, but it soon becomes apparent that they must be swept from the field, or perish there where they are doing so well, so thick and over-whelming a storm of Rebel fire involves them. It was fearful to see, but these men, such as ever escape, must come from that conflict as best they can. To move down and support them with other troops is out of the question, for this would be to do as Sickles did, to relinquich <sic> a good position, and advance to a bad one. There is no other alternative - the Third Corps must fight itself out of its position of destruction! What was it ever put there for?

In the meantime some other dispositions must be made to meet the enemy, in the event that Sickles is overpowered. With this Corps out of the way, the enemy would be in a position to advance upon the line of the Second Corps, not in a line parallel with its front, but they would come obliquely from the left.

To meet this contingency the left of the Second Division of the Second Corps is thrown back slightly, and two Regiments, the 15th Mass., Col. Ward, and the 82nd N.Y., Lieut. Col. Horton, are advanced down to the Emmetsburg road, to a favorable position nearer us than the fight has yet come, and some new batteries from the artillery reserve are posted upon the crest near the left of the Second Corps.

This was all Gen. Gibbon could do. Other dispositions were made or were now being made upon the field, which I shall mention presently. The enemy is still giving Sickles fierce battle - or rather the Third Corps, for Sickles has been borne from the field minus one of his legs, and Gen. Birney now commands - and we of the Second Corps, a thousand yards away, with our guns and men are, and must be, still idle spectators of the fight.

The Rebel, as anticipated, tries to gain the left of the Third Corps, and for this purpose is now moving into the woods at the west of Round Top. We knew what he would find there. No sooner had the enemy gotten a considerable force into the woods mentioned, in the attempted execution of his purpose, than the roar of the conflict was heard there also. The Fifth Corps and the First Division of the Second were there at the right time, and promptly engaged him; and there, too, the battle soon became general and obstinate.

Now the roar of battle has become twice the volume that it was before, and its range extends over more than twice the space. The Third Corps has been pressed back considerably, and the wounded are streaming to the rear by hundreds, but still the battle there goes on, with no considerable abatement on our part. The field of actual conflict extends now from a point to the front of the left of the Second Corps, away down to the front of Round Top, and the fight rages with the greatest fury. The fire of artillery and infantry and the yells of the Rebels fill the air with a mixture of hideous sounds.

When the First Division of the Second Corps first engaged the enemy, for a time it was pressed back somewhat, but under the able and judicious management of Gen. Caldwell, and the support of the Fifth Corps, it speedily ceased to retrograde, and stood its ground; and then there followed a time, after the Fifth Corps became well engaged, when from appearances we hoped the troops already engaged would be able to check entirely, or repulse the further assault of the enemy.

But fresh bodies of the Rebels continued to advance out of the woods to the front of the position of the Third Corps, and to swell the numbers of the assailants of this already hard pressed command.

The men there begin to show signs of exhaustion - their ammunition must be nearly expended - they have now been fighting more than an hour, and against greatly superior numbers. From the sound of the firing at the extreme left, and the place where the smoke rises above the tree tops there, we know that the Fifth Corps is still steady, and holding its own there; and as we see the Sixth Corps now marching and near at hand to that point, we have no fears for the left - we have more apparent reason to fear for ourselves.

The Third Corps is being overpowered - here and there its lines begin to break - the men begin to pour back to the rear in confusion-the enemy are close upon them and among them-organization is lost to a great degree-guns and caissons are abandoned and in the hands of the enemy-the Third Corps, after a heroic but unfortunate fight, is being literally swept from the field. That Corps gone, what is there between the Second Corps, and these yelling masses of the enemy?

Do you not think that by this time we began to feel a personal interest in this fight? We did indeed. We had been mere observers - the time was at hand when we must be actors in this drama.

Up to this hour Gen. Gibbon had been in command of the Second Corps, since yesterday, but Gen. Hancock, relieved of his duties elsewhere, now assumed command. Five or six hundred yards away the Third Corps was making its last opposition; and the enemy was hotly pressing his advantages there, and throwing in fresh troops whose line extended still more along our front, when Generals Hancock and Gibbon rode along the lines of their troops; and at once cheer after cheer-not Rebel, mongrel cries, but genuine cheers-rang out all along the line, above the roar of battle, for "Hancock" and "Gibbon," and "our Generals." These were good. Had you heard their voices, you would have known these men would fight.

Just at this time we saw another thing that made us glad: - we looked to our rear, and there, and all up the hillside which was the rear of the Third Corps before it went forward, were rapidly advancing large bodies of men from the extreme right of our line of battle, coming to the support of the part now so hotly pressed.

There was the whole Twelfth Corps, with the exception of about one brigade, that is, the larger portion of the Divisions of Gens.Williams and Geary; the Third Division of the First Corps, Gen. Doubleday; and some other brigades from the same Corps-and some of them were moving at the double quick. They formed lines of battle at the foot of the Taneytown road, and when the broken fragments of the Third Corps were swarming by them towards the rear, without halting or wavering they came sweeping up, and with glorious old cheers, under fire, took their places on the crest in line of battle to the left of the Second Corps. Now Sickles' blunder is repaired.

Now, Rebel chief, hurl forward your howling lines and columns! Yell out your loudest and your last, for many of your best will never yell, or wave the spurious flag again!

The battle still rages all along the left, where the Fifth Corps is, and the West slope of Round Top is the scene of the conflict; and nearer us there was but short abatement, as the last of the Third Corps retired from the field, for the enemy is flushed with his success. He has been throwing forward brigade after brigade, and Division after Division, since the battle began, and his advancing line now extends almost as far to our right as the right of the Second Division of the Second Corps.

The whole slope in our front is full of them; and in various formation, in line, in column, and in masses which are neither, with yells and thick volleys, they are rushing towards our crest. The Third Corps is out of the way. Now we are in for it. The battery men are ready by their loaded guns. All along the crest is ready.

Now Arnold and Brown - now Cushing, and Woodruff, and Rhorty! - you three shall survive to-day! They drew the cords that moved the friction primers, and gun after gun, along the batteries, in rapid succession, leaped where it stood and bellowed its canister upon the enemy. The enemy still advance.

The infantry open fire - first the two advance regiments, the 15th Mass. and the 82d N. Y. - then here and there throughout the length of the long line, at the points where the enemy comes nearest, and soon the whole crest, artillery and infantry, is one continued sheet of fire. From Round Top to near the Cemetery stretches an uninterrupted field of conflict. There is a great army upon each side, now hotly engaged.

To see the fight, while it went on in the valley below us, was terrible, - what must it be now, when we are in it, and it is all around us, in all its fury? All senses for the time are dead but the one of sight. The roar of the discharges and the yells of the enemy all pass unheeded; but the impassioned soul is all eyes, and sees all things, that the smoke does not hide. How madly the battery men are driving home the double charges of canister in those broad-mouthed Napoleons, whose fire seems almost to reach the enemy. How rapidly these long, blue-coated lines of infantry deliver their file fire down the slope.

But there is no faltering - the men stand nobly to their work. Men are dropping dead or wounded on all sides, by scores and by hundreds, and the poor mutilated creatures, some with an arm dangling, some with a leg broken by a bullet, are limping and crawling towards the rear. They make no sound of complaint or pain, but are as silent as if dumb and mute. A sublime heroism seems to pervade all, and the intuition that to lose that crest, all is lost. How our officers, in the work of cheering on and directing the men, are falling.

We have heard that Gen. Zook and Col. Cross, in the First Division of our Corps, are mortally wounded-they both commanded brigades, - now near us Col. Ward of the 15th Mass.- he lost a leg at Balls Bluff-and Lieut. Col. Horton of the 82d N. Y., are mortally struck while trying to hold their commands, which are being forced back; Col. Revere, 20th Mass., grandson of old Paul Revere, of the Revolution, is killed, Lieut. Col. Max Thoman, commanding 59th N. Y., is mortally wounded, and a host of others that I cannot name. These were of Gibbon's Division.

Lieut. Brown is wounded among his guns - his position is a hundred yards in advance of the main line-the enemy is upon his battery, and he escapes, but leaves three of his six guns in the hands of the enemy. The fire all along our crest is terrific, and it is a wonder how anything human could have stood before it, and yet the madness of the enemy drove them on, clear up to the muzzle of the guns, clear up to the lines of our infantry-but the lines stood right in their places.

Gen. Hancock and his Aides rode up to Gibbon's Division, under the smoke. Gen. Gibbon, with myself, was near, and there was a flag dimly visible, coming towards us from the direction of the enemy. "Here, what are these men falling back for?" said Hancock.

The flag was no more than fifty yards away, but it was the head of a Rebel column, which at once opened fire with a volley. Lieut. Miller, Gen. Hancock's Aide, fell, twice struck, but the General was unharmed, and he told the 1st Minn., which was near, to drive these people away.

That splendid regiment, the less than three hundred that are left out of fifteen hundred that it has had, swings around upon the enemy, gives them a volley in their faces, and advances upon them with the bayonet. The Rebels fled in confusion, but Col. Colville, Lieut. Col. Adams and Major Downie, are all badly, dangerously wounded, and many of the other officers and men will never fight again. More than two-thirds fell.

Such fighting as this cannot last long. It is now near sundown, and the battle has gone on wonderfully long already. But if you will stop to notice it, a change has occurred. The Rebel cry has ceased, and the men of the Union begin to shout there, under the smoke, and their lines to advance.

See, the Rebels are breaking! They are in confusion in all our front! The wave has rolled upon the rock, and the rock has smashed it. Let us shout, too!

First upon their extreme left the Rebels broke, where they had almost pierced our lines; thence the repulse extended rapidly to their right. They hung longest about Round Top, where the Fifth Corps punished them, but in a space of time incredibly short, after they first gave signs of weakness, the whole force of the Rebel assault along the whole line, in spite of waving red flags, and yells, and the entreaties of officers, and the pride of the chivalry, fled like chaff before the whirlwind, back down the slope, over the valley, across the Emmetsburg road, shattered, without organization in utter confusion, fugitive into the woods, and victory was with the arms of the Republic.

The great Rebel assault, the greatest ever made upon this continent, has been made and signally repulsed, and upon this part of the field the fight of today is now soon over. Pursuit was made as rapidly and as far as practicable, but owing to the proximity of night, and the long distance which would have to be gone over before any of the enemy, where they would be likely to halt, could be overtaken, further success was not attainable today.

Where the Rebel rout first commenced, a large number of prisoners, some thousands at least, were captured; almost all their dead, and such of their wounded as could not themselves get to the rear, were within our lines; several of their flags were gathered up, and a good many thousand muskets, some nine or ten guns and some caissons lost by the Third Corps, and the three of Brown's battery - these last were in Rebel hands but a few minutes- were all safe now with us, the enemy having had no time to take them off.

       Charles W. Eliot, ed. American Historical Documents. (1910): 327-353.

Reprinted from public domain on the Internet.