But the battle was ended. Toward morning, it was known to officers of our corps that the rebels were moving back, and the fact was reported; but no attention was paid to it. A truce, under pretense of burying the dead, gave the rebels a quiet day, in which to prepare for their escape, by sending their trains and much of their artillery to the rear; and on the night of the 18th, the whole rebel army disappeared. So this memorable and sanguinary battle ended. A defeat for the rebels, but not the decided victory to our arms that could have been hoped for.

The Second division of the Sixth corps was relieved soon after noon of the 18th by Couch's division, which was soon afterward joined to the Sixth corps. Until now our corps had consisted of but two divisions, the First and Second. Our men were glad to fall back enough to allow them to cook their coffee once more, and they proceeded to the work of preparing a good meal with great spirit.

The scene on the battle-field was past description. The mangled forms of our own comrades lay stretched upon the ground, side by side with those of the rebels. On almost every rod of ground over one hundred acres, the dead and wounded, some clad in the Union blue and some in confederate gray, were lying. A ghastly sight, presenting all the horrible features of death which are to be seen on such a field. At one point in our own front, for more than half a mile, the rebels lay so thickly as almost to touch each other. On the field where Hooker's men had won and lost the field, the dead and dying were scattered thickly among the broken cornstalks, their eyes protruding and their faces blackened by the sun. Wherever the lines of battle had surged to and fro, these vestiges of the terrible work were left. In the edge of the wood, where the rebels had made a stand against Hooker's advancing divisions, the bodies lay in perfect line, as though they had fallen while on dress parade. Further to the left there was a narrow road, not more than fifteen feet wide, with high fences on either side. Here a regiment of rebels was posted; when our batteries getting an enfilading fire upon them, and the infantry at the same time opening a murderous fire, the regiment was literally destroyed; not more than twenty of their number escaping. Their bodies filled the narrow road. Some were shot while attempting to get over the fence; and their remains hung upon the boards. A more fearful picture than we saw here, could not be conceived.

Broken caissons, wheels, dismounted guns, thousands of muskets, blankets, haversacks and canteens, were scattered thickly over the field; and hundreds of slain horses, bloated and with feet turned toward the sky, added to the horror of the scene.

While the excitement of battle lasts, and we hear the roar of artillery, and the shock of contending armies, the terrible reality of the occasion hardly presents itself to our minds, and it is only when we survey the bloody field, strewed with the mangled, lifeless remains of friend and foe, or walk through the hospitals, where the unfortunate victims of battle writhe in the agony of their wounds, that we realize the terrible nature of a great battle.

Sickening as is the sight of the battle-field, the scenes about the hospitals are worse, except to those who are actually engaged in ministering to the relief of the wounded. To these the excitement and labor incident to their duties, crowd out the thoughts of the ghastly surroundings. They see only so many demands upon them for assistance, and have no time to indulge in sentimental emotions.

Here in the rear of the army for miles, was a succession of hospitals. Every house, and barn, and haystack, formed the nucleus of a hospital, where men, shot through the head, through the limbs, through the body; with every conceivable variety of wounds, lay groaning in anguish. Surgeons toiled day and night with never lagging zeal to relieve these sufferings, but all their labor could only afford slight relief. The labors of medical officers after a great battle are immense, and there is no respite from their toils so long as a wounded man remains uncared for. While others find repose from the fatigues of battle in sleep, the surgeons are still at work; there is no sleep for them so long as work remains to be done.

The rebel army had fallen back; yet a skirmish line had been left to cover the movement. At length even this suddenly disappeared, and, firing a few solid shots, as a parting salute, the enemy took a final leave of the field. Our forces were ordered on. We passed over the scene of carnage, where hundreds of dead lay still unburied; and pioneers were on every part of the field throwing the mangled, disfigured forms into shallow graves. Along the roadsides, under the fences, and where the confederate hospitals had been, still these gory objects met our view. We reached Sharpsburgh, and here the evidences of the terrible conflict were to be seen everywhere. Houses riddled by shells and bullets; some of them destroyed by fire, and some battered into shapeless masses; the streets filled with disabled wagons; horses galloping about without riders; knapsacks, guns and equipments cast away in the hasty flight; churches filled with rebel wounded; all helped to make up a scene of destruction such as has been rarely witnessed. The people of the village welcomed us as their deliverers, and brought water, and such other refreshments as they had been able to conceal from the rebels. We passed the village and bivouacked for the night.

On the 20th, we, of the Sixth corps, retraced our steps, passing again over the battle-field, where the stench was now unendurable. We reached Williamsport at daylight, where Couch's division was face to face with the enemy, who were said to be recrossing the river, and who had last night forced back part of the division.

The rebel force had, however, consisted of about four thousand cavalry, who, finding the Unionists in force, quickly returned to the south side of the Potomac. Here we found an immense division of Pennsylvania militia drawn up in line of battle. Its regiments were larger than our brigades. They were armed with every variety of fire-arms, from light sporting shot-guns to Sharpe's rifles. Their uniforms had quite as little uniformity as their arms. Some were dressed in gray pants and jackets, others in light blue; and still others in the various fashions which constituted the wearing apparel at home. Grave gentleman in spectacles, studious young men in green glasses, pale young men who were evidently more at home behind the counter than in line of battle, roughs who had not been tamed by the discipline of military life, and boys who, for the first time, had left the paternal mansion, made up the heterogeneous division.