Our own forces were also gathering toward this point. Richardson's division of the Second corps, pressing closely upon the heels of the retreating rebels, had passed through Boonsboro and Keedeysville, and had overtaken them here.

Porter, with his regulars, was close at hand, and took position. Then came Burnside, with his favorite Ninth corps; and the white-haired veteran, Sumner, with troops worthy of their leader; fighting Joe Hooker and his gallant men; and Mansfield, with Banks' corps. The afternoon and most of the night was spent in getting into position. Brisk skirmishes were occurring with sufficient frequency to excite the men on both sides; but no general engagement took place. The morning of the 16th found our army ready to give battle. On our right was Hooker; then Sumner with his own and the Twelfth, Mansfield's corps; and far to the left was Burnside. Porter's corps, secure behind an elevation in the rear, was held in reserve.

The night had passed with but now and then a little picket firing; but all felt that, before many hours, must commence a battle, which must determine the fate at least of that campaign.

Crossing the Antietam, in front of the line of our army, were three bridges. The first, on the Hagerstown road; the next on the road to Sharpsburgh; and the third on the left, three miles below, on the road from Harper's Ferry to Sharpsburgh.

This last bridge, crossed the stream at a point where steep and high hills crowded closely on every side; the summits of those on the western side of the stream, crowned with rebel batteries, and their steeply falling sides covered with infantry. Over the first of these bridges, on the right, Hooker was to cross his forces; while on the left, Burnside was to attempt to dislodge the enemy from his commanding position. Far in the rear, a prominent hill rose above the surrounding country; here was a signal station, and here the commander of the army established his quarters. Hour after hour of the 16th passed away, the two armies facing each other, watching and waiting; troops moving this way and that, maneuvering like two giant wrestlers, each willing to try the movements and feel the gripe of the other before coming to the sharp grapple. At four o'clock, Hooker crossed his corps and occupied a position on the west side of the creek, and Mansfield soon followed; a little fighting, but not severe, and then darkness closed over the scene again. The skirmishes and artillery practice here, developed, to the quick eye of General Hooker, the position of the enemy in his front, and their plan of defense. Satisfied with this knowledge, he was willing to allow his corps to rest until morning. Our lines were now very near those of the rebels; so near that the pickets of the opposing forces could hear conversation from one line to the other.

At an early hour on the morning of the 17th, the great battle commenced in earnest. Hooker formed his line with Doubleday on the right, Meade in the center, and Ricketts on the left. Opposed to him was Stonewall Jackson's corps. First, Meade's Pennsylvania reserves, of Hooker's corps, opened upon the enemy, and in a few moments the firing became rapid and general along the line of both Meade's and Rickett's divisions. The rebel line of battle was just beyond the woods, in a cornfield. The hostile lines poured into each other more and more deadly volleys; batteries were brought up on each side which did terrible execution. Each line stood firm and immovable. Although great gaps were made in them, they were closed up, and the opposing forces continued to pour fearful destruction into each other's ranks. General Hooker, riding everywhere along the front line, knew exactly the position and the work of every regiment in his command. Cheer after cheer greeted him as he passed along the line, inspiring the men by his presence. Thus for half an hour the two lines stood face to face in deadly conflict; at length the general directed a battery to be placed in a commanding position, and the shells and shrapnel were seen to work fearful havoc in the rebel ranks. The gray line wavered; then back through the cornfield and over the fences the confederates rushed, seeking shelter from the terrible storm, under cover of the woods, on the other side of the field. "Forward!" shouted General Hooker, and his divisions pressed rapidly through the cornfield, up to the very edge of the wood, while the welkin rang with their cheers. Here, the fleeing foe, reinforced by fresh troops, made a determined stand. Terrific volleys poured from the woods, thinning out the Union ranks at a fearful rate. Unable to sustain the deadly fire, they fell back—this time the rebels following with yells and shouts; but before the cornfield was crossed, our troops made another stand, and the swarthy foe was brought to bay; yet the thinned line seemed hardly able to sustain the fearful shock much longer. Hooker, fearing that his center was doomed to destruction, sent to his right for a brigade, although his right was hard pressed and in danger of being flanked.

The fresh brigade pressed steadily to the front, and the rebel line again fell back to the woods. Mansfield's corps now came to the support of the right wing, and well did those troops, so lately demoralized at Bull Run, stand their ground. General Mansfield received here his mortal wound.

It was at this time, when Hooker saw his forces gaining a decided advantage and felt that their part of the work was well done, that a rifle ball passed through his foot inflicting a painful wound. Lamenting that he could not remain to see the end of what he hoped would prove a great victory, he left the field. The battle lulled at this point; but in the center it raged with terrible energy. There, Sumner the white-haired veteran, led his corps into the very jaws of death. If he seemed reckless of the lives of his men, he had no more care of his own. Across the ploughed ground, over ditches and fences, with unsurpassed ardor, sweeping over all obstacles, the corps pushed forward, driving the enemy before it; but the right became hard pressed, and a terrible fire on that part of the line and on the center, forced the corps back. Again the ground was taken; and again the enemy, with wild yells of triumph, drove our men back. Still determined to win, the veteran hero ordered a third charge; and the third time the field was ours, but only to be lost again. The brave General Sedgwick, who then led one division of Sumner's corps, whom we were afterward proud to call the commander of the Sixth corps, thrice wounded, was at length obliged to leave the field. Richardson and Crawford were carried wounded to the hospitals.

It was at this critical moment, when Sumner's troops, weary and almost out of ammunition, were for the third time repulsed; the remnants of the shattered regiments no longer able to resist the overwhelming forces opposed to them; the artillery alone, unsupported, holding the enemy for a moment in check; that the Sixth corps, our second division in advance, arrived upon the field.

The scene before us was awful. On the left, as far as the eye could reach, the lines of the contending forces, stretching over hills and through valleys, stood face to face; in places, not more than thirty yards apart. The roar of musketry rolled along the whole extent of the battle-field. The field upon which we had now entered, thrice hotly contested, was strewed with the bodies of friend and foe.