General Robert E. Lee’s Confederate Army of Northern Virginia withdrew across the Potomac River and out of Maryland through the dark early morning of September 19. Major General A.P. Hill’s “Light Division” and Brigadier General Fitzhugh Lee’s cavalry served as rear guard. The last Confederate infantrymen waded across the Potomac near dawn. When Lee was informed that his army was now back in Virginia (except for an artillery battery and the ambulance wagons), Lee replied, “Thank God!” He directed Brigadier General William N. Pendleton to guard Boteler’s Ford, which the Federals would use to pursue the Confederates across the river. Pendleton had two brigades and 45 guns.
Men of the Federal Army of the Potomac, positioned east of Sharpsburg, could hear the Confederates pulling out of their line and marching out of Maryland all through the night. Major General George B. McClellan, army commander, dispatched the Fifth Corps under Major General Fitz John Porter and the cavalry to confirm that the Confederates were gone. The Federals advanced to the banks of the Potomac and exchanged fire with enemy troops across the river.
McClellan boasted to his superiors, “I have the honor to report that Maryland is entirely freed from the presence of the enemy, who has been driven across the Potomac. No fears need now be entertained for the safety of Pennsylvania. We may safely claim a complete victory.” He proudly informed his wife Ellen, “Our victory was complete. I feel some little pride in having with a beaten and demoralized army defeated Lee so utterly, & saved the North so completely.”
Political allies of McClellan celebrated his success as a success for the Democratic Party and a repudiation of the Radical Republican (and the Lincoln administration) agenda. A government clerk wrote to Samuel Barlow, one of McClellan’s most influential backers: “McClellan is the acknowledged man. Unless I much mistake me, henceforth he will have a party that shall bestride these lilliputians. I think a new and conservative era has commenced; & that the day of little men & demagogues is waning.”
Yet McClellan did little to follow up his “complete victory,” and he missed a chance to destroy the Confederates as they crossed the Potomac. Navy Secretary Gideon Welles wrote in his diary, “Nothing from the army, except that, instead of following up the victory, attacking and capturing the Rebels, they… are rapidly escaping across the river… Oh dear!”
McClellan was deeply disturbed to receive an admonition, and not congratulations, from General-in-Chief Henry W. Halleck for failing to keep Washington more closely informed of what was happening. McClellan angrily responded: “I regret that you find it necessary to couch every dispatch I have the honor to receive from you, in a spirit of fault finding, and that you have not yet found leisure to say one word in commendation of the recent achievements of this Army, or even to allude to them.”
Meanwhile near dusk, Porter deployed two brigades that attacked Pendleton’s Confederates and drove them away from Boteler’s Ford. Pendleton could not see the action in the dark and hurriedly reported to Lee that the Federals had captured all 45 guns. Lee responded by sending Major General Thomas J. “Stonewall” Jackson’s Confederates to regain the cannon and drive the Federals back into Maryland.
Jackson deployed A.P. Hill’s division on the morning of the 20th. The Confederates formed two assault lines, advanced through Federal artillery fire, and drove the enemy back across the river. The 118th Pennsylvania, also known as the “Corn Exchange Regiment,” sustained heavy casualties after being pushed over a bluff and then fired upon from above while trying to escape.
The Federals suffered 363 casualties while the Confederates lost 261. Pendleton had been wrong; the Federals captured only five of the Confederates’ 45 guns, one of which was regained by Hill’s men. He was relegated to desk duty following this engagement. This skirmish secured Lee’s rear and enabled him to complete his withdrawal to Opequon Creek, near Martinsburg in western Virginia, where he could rest and retool his army. He had just 36,418 infantrymen present for duty, many of whom lacked adequate clothing or footwear.
Back at the Antietam battlefield, Federals were still hard at work burying corpses, many of which were swelling and turning black under the hot sun. An officer wrote, “The Antietam turnpike surpassed all in manifest evidence of slaughter.” Another noted that he could walk all the way across the Cornfield without ever having to touch the ground. Confederates were buried in long trenches, while Federal comrades, if identified, were given individual graves.
McClellan wasted little time in trying to convert his “complete victory” into political clout. He wrote Ellen:
“An opportunity has presented itself through the Governors of some of the states to enable me to take my stand. I have insisted that (Secretary of War Edwin) Stanton shall be removed and that Halleck shall give way to me as Commander in Chief. I will not serve under him–for he is an incompetent fool–in no way fit for the important place he holds… The only safety for the country & for me is to get rid of lots of them… I have shown that I can fight battles and win them! I think my enemies are pretty effectively killed by this time.”
McClellan reiterated these demands in another letter to his wife that same day:
“I hope that my position will be determined this week. Through certain friends of mine I have taken the stand that Stanton must leave & that Halleck must restore my old place to me. Unless these two conditions are fulfilled I will leave the service. I feel that I have done all that can be asked in twice saving the country. If I continue in its service I have at least the right to demand a guarantee… You should see my soldiers now! You never saw anything like their enthusiasm. It surpasses anything you ever imagined.”
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