During the active part of this campaign General McClellan was detained, by order of General Halleck, at Alexandria and ordered to forward his troops as fast as they arrived from Harrison's Landing to join Pope's army. This he did and they had all joined us in time to take part in the battles of Groveton and the second Bull Run, except Franklin's and Sumner's corps, who were still on the march. General McClellan then found himself in the singular position of a commanding general stripped of his army, with nothing but a few orderlies and small camp guard. General Pope had sent a very favorably colored report of the second Battle of Bull Run to General Halleck; but the next day Colonel J. C. Kelton, A.A.G., was sent from the War Department to Pope's army, and upon his return on September second reported the true condition of affairs, which alarmed the President and Cabinet and terrified the city of Washington. Pope's army was ordered to retreat immediately within the fortifications of Washington for the protection of the city. The administration now turned toward McClellan again and placed him in command of the defenses of Washington and the troops of Pope's defeated army as they arrived within the fortifications.
The morning after the battle, August thirty-first, during a cold rain, we were marched within the old Confederate works at Centreville and encamped there. The day was quiet, but toward night there was a rumor that a part of the Rebel army was on the move to turn our right and intersperse between us and Washington. Next morning two army corps were ordered to march in the direction of Chantilly, where that afternoon a severe battle was fought which resulted in a victory for the Union arms. Among our losses was the daring one-armed General Kearney, one of the bravest officers in our army.
It was a race now to see which army would get to Washington first. We could hear the firing at Chantilly and, while it was still going on the Fifth Corps received orders to proceed to Fairfax Court House in a hurry. After a weary night-march we arrived there on the morning of September second and went into bivouac. The following morning we resumed our march, taking the road towards Washington. The enemy was close on our flank and there was some skirmishing just after leaving Fairfax Court House. Late in the afternoon we saw the dome of the Capitol and kept on, weary with the long march, until after dark, when during a halt, we heard loud cheering in front. Soon word was passed along that General McClellan had come out to meet us, and the cheering was taken up by the entire corps. The General had only a very small escort of soldiers and one officer with him, but his presence cheered us and revived our depressed spirits. We felt that Washington was safe.
The Fifth Corps encamped for several days on Hall's Hill. While at this camp the skeleton battalions of the Second and Tenth United States Infantry were consolidated under the command of Captain Poland of the Second Infantry, the ranking officer, and henceforth we were designated as the Battalion of the Second and Tenth Infantry; company formations were not interfered with.
With the arrival of the army within the defenses of Washington the enemy disappeared and on the fifth of September were reported to be crossing the Potomac into Maryland. The cavalry of the Army of the Potomac was promptly started on the march and quickly followed by the artillery and infantry. The Fifth Corps left on the evening of the sixth and crossed the Potomac on the Chain Bridge, then marched by way of Tennalytown, Rockville and Monocacy to Frederick City, where we arrived the twelfth of September. The roads were good, but very dusty; the country was well cultivated and we got some fruit and plenty of green corn on the way, roasting the ears at our camp-fires.
Next day our march was across the mountains to the Middletown Valley, where we encamped near the foot of South Mountain. We could hear the guns at Harper's Ferry, which was besieged by Stonewall Jackson. On the afternoon and evening of the fourteenth General Reno had a battle at Turner's Pass on South Mountain, part of which was visible from our camps. The Rebels were driven from the mountain and retreated toward Sharpsburg during the night. General Reno was killed near the close of this action.
On the morning of the fifteenth we crossed the Blue Ridge by the road across South Mountain leading to Sharpsburg, passing a part of the battlefield, where we saw a number of dead Confederates beside the road and in the fields where they had fallen the evening before. In descending the western slope of the South Mountain we had some fine views of the valley of the Antietam, the great fields of grain, orchards and farm-houses—a beautiful picture of peace and plenty, soon to be destroyed by the horrors of war. Our march was toward the Central Bridge over the Antietam on the pike leading to Sharpsburg, where we took up a position on the left of the road. The Rebels had batteries on the opposite side of the Antietam on high ground, which opened on us as soon as they saw us approaching; but they did us no damage and we were soon under cover where their fire was returned by two of our batteries.
The great Battle of Antietam, in which more than one hundred and fifty thousand men and some hundreds of pieces of artillery were engaged on the sixteenth and seventeenth days of September, is well described in histories and was decidedly a Union victory. General McClellan is severely criticized for allowing Lee and his army to escape across the Potomac on the night of the eighteenth, and General Burnside for dilly-dallying and delaying his attack on bridge number three, where he could not see his glorious opportunity.
Porter's Fifth Army Corps held an important position in the center of the line covering the reserve artillery and wagon-trains on the east bank of the Antietam. It was here, in the center, that General McClellan was most anxious that his line should not be broken, and he relied on General Porter for that. The Fifth Corps was not engaged as a body in this battle, but some brigades were detached from it at various times to reinforce other parts of the field. We were much exposed to the enemy's artillery fire and sharp-shooters at times. On the second day of the battle my battalion, the Second and Tenth, were ordered to cross the bridge about four P.M. to protect some light batteries on the opposite side of the Antietam. We deployed as skirmishers to the left of the road and while passing over a ridge were fired at by the Rebel sharp-shooters and by a battery with canister shot. We sustained considerable loss but kept on as far as a fence, where we halted and commenced a fire which soon caused the enemy's cannoneers to leave their guns; and although soon reinforced by a part of the First Brigade, we were not considered strong enough to charge and take this battery and were ordered by one of General Sykes's aides-de-camp to withdraw from our dangerous position to a place of cover, where we remained until sun-down and then re-crossed the bridge and returned to our former position. Our small battalion lost about fifty of its number, killed and wounded, in this engagement.
The day after the battle we remained quietly in our position. The Rebels, under flags of truce, were picking up their wounded and burying some of their dead, while squads from our army performed the same sad duties.