The Battle of Antietam: Afternoon

This entry is part 10 of 11 in the series The Maryland Campaign

The Battle of Antietam:


The final chapter in the bloody Battle of Antietam took place on the afternoon of September 17, 1862 at the southern end of the battlefield. Maj. Gen. Ambrose Burnside‘s IX Corps had been assigned a diversionary role in Union commander Maj. Gen. George B. McClellan’s battle plan.

While Maj. Gen. Joseph Hooker’s I Corps was to make the main attack at the northern end of the Confederate defensive positions, Burnside’s troops were to attack across the Lower Bridge in order to draw Confederate troop strength south.

Burnside was ordered to wait until he received explicit orders to attack. The battle raged for 4 1/.2 hours before he received those orders at 10:00 AM. Burnside was simmering because of the role that his men had been assigned and the fact that he no longer was a “wing” commander, overseeing both the I and IX Corps.

Map of the Battle of Antietam, Burnside's assaultsBurnside had four divisions that included 12,500 men and 50 guns. His divisions were led by Brig. Gens. Orlando B. WillcoxSamuel D. Sturgis,  Isaac P. Rodman and the Kanawha Division, under Col. Eliakim P. Scammon.

Click Map to enlarge.

By 10:00 AM, the Confederate force that opposed his formidable force consisted of only one division, the 3,000 men and 12 guns of Brig. Gen. David R. Jones. Lee had moved Brig. Gen. John G. Walker‘s Division to the northern end of the battlefield as McClellan had hoped that he would.

Jones had positioned four under-strength brigades along the ridges south of Sharpsburg, primarily on a low plateau known as cemetary hill. He had the 400 men of the 2nd and 20th Georgia regiments, under the command of Brig. Gen. Robert Toombs, with two artillery batteries defending Rohrbach’s Bridge (The actual name of the Lower Bridge).

Rohrbach’s Bridge, which would later become known as Burnside’s Bridge, is perhaps the one iconic symbol that people will remember about the Battle of Antietam. It is a 125 foot long, three-span, stone structure that became the centerpiece of the Burnside’s struggle to cross Antietam Creek.

It was a particularly difficult crossing for the Union troops. The road leading to the bridge ran parallel to the creek so that the Union troops were exposed to Confederate fire as they prepared to move across the bridge. The Confederate troops were positioned on a 100-foot bluff on the western side of the creek with excellent cover for their sharpshooters because of the woods and rocks.

Burnside has been roundly criticized for not fording the creek out of sight of the Confederate troops. At this point it was no more than 50 feet wide and at most waist deep. It would have been comparatively easy to move troops across the creek and flank the Confederate defensive positions.

Instead, Burnside ordered a straight-forward assault across the bridge combined with fording the creek about a half mile downstream. When his troops arrived at the ford, they found that the banks were to steep to negotiate. This option was abandoned early on and the assault became his only means of crossing.

Burnside did send additional troops on a futile march 2 miles further south to Snavely’s Ford but their mission was unsuccessful and only served toGeneral Ambrose Burnside  remove them from the greater part of the battle.

Col. George Crook‘s Ohio brigade made the initial assault across the bridge, led by skirmishers from the 11th Connecticut. Their assignment was to clear the bridge area of Confederate sharpshooters. After a furious 15-minute battle, they withdrew after losing 139 men, one-third of their strength, including their commander who was fatally wounded. Crook’s men were able to get across and drifted to the north, where they exchanged fire with the Confederates for the next several hours.

The second assault from Sturgis’ division fell apart under enemy fire from sharpshooters and artillery. Meanwhile, McClellan was sending a series of dispatches to Burnside urging him to press on. “Tell him if it costs 10,000 men he must go now,” he ordered one aide. He increased the pressure by sending his inspector general, Col. Delos B. Sackett, to confront Burnside, who reacted indignantly: “McClellan appears to think I am not trying my best to carry this bridge; you are the third or fourth one who has been to me this morning with similar orders.”

At about 12:30 PM, Burnside’s third attempt began. Brig. Gen. Edward Ferrero‘s brigade spearheaded the assault with the 51st New York and the 51st Pennsylvania leading the attack. They used a captured light howitzer and fired double canister down the bridge and got within 25 yards of the enemy. The successfully crossed the bridge and Toombs was forced to order a withdrawal when he received word that Union troops had crossed at Snavely’s Ford.

The Confederate defense had successfully stalled the Union attack for about three hours at the cost of less than 160 casualties while inflicting about more than 500 on Burnside’s troops. They also bought time for Confederate reinforcements under Maj. Gen. A.P. Hill to arrive from Harpers Ferry.

Burnside's BridgeBurnside was now across the creek but his offense stalled due to a lack of ammunition. His logistics officers had not brought sufficient small arms and artillery ammunition. The narrow bridge was itself a bottleneck for the troops, artillery and supply wagons. It took about two hours to clear this up and resupply the Union troops.

Meanwhile, A.P. Hill‘s Light Division began to arrive after an exhausting 17-mile forced march from Harpers Ferry. They had been assigned to supervise the paroles of the captured Union garrison and secure the captured supplies. At 2:30 PM Hill met with Lee who ordered him to position his division to Jones’ right. Hill’s Light Division would add an additional 3,000 men to the Confederate defensive line.

Burnside was unaware of their pending arrival and had formulated a plan to move around the Confederate right in the exact spot that Hill’s men now were situated. At about 3:00 PM Burnside left Sturgis’ Division in reserve and moved west with 8,000 men and 22 guns.

Burnside’s assault met with initial success that caused panic to run through the Confederates in Sharpsburg, who began retreating through the town. With the exception of Toombs’ Brigade the balance of Jones’ Division had lost all unit cohesion under the Union assault. Toombs only had 700 men with which to hold of the Union attack.

Then, like the proverbial cavalry, Hill’s five brigades arrived at about 3:30 PM. He assigned two of them to the southeast to guard his flank. The other three, about 2,000 men, moved to the right of Toombs’s brigade and prepared for a counterattack. Brig. Gen. Maxcy Gregg‘s brigade of South Carolinians attacked the oncoming Union flank, cutting through three regiments. This blunted the Union advance and unnerved Burnside.

Having lost 20% of his strength, Burnside ordered his corps all of the way back to the west bank of Antietam Creek. He urgently requested more Dead Confederate Soldiers at Antietammen and guns to renew his attack but McClellan responded, “I can do nothing more. I have no infantry.”

In fact, McClellan had two infantry corps in reserve, Porter’s V Corps and Franklin’s VI Corps. McClellan once again lost a chance to crush the Confederate army because of his caution and fear of Lee’s supposed strength. Burnside’s men remained to guard the bridge that had cost them so much to capture. By 5:30 PM all fighting had ceased as both armies were exhausted.

The Battle of Antietam was the bloodiest single-day battle in American history and remains today the bloodiest day in American history. The Union had 12,401 casualties with 2,108 dead. Confederate casualties were 10,318 with 1,546 dead. This represented 25% of the Federal force and 31% of the Confederate.

Several generals died as a result of the battle, including Maj. Gens. Joseph K. Mansfield and Israel B. Richardson and Brig. Gen. Isaac P. Rodman on the Union side (all mortally wounded), and Brig. Gens. Lawrence O. Branch and William E. Starke on the Confederate side (killed). Numerous other division, brigade and regimental commanders were killed or wounded.

On September 18th, Lee prepared his army for an attack that never came. Instead, their was a truce for both sides to recover their wounded. By the end of the day, the Confederates began their return to the Potomac and back into Virginia.

Citing shortages in men and equipment, McClellan refused to move into Virginia, despite repeated entreaties from the War Department and the president himself. The Union army remained in Maryland until October 26th. Lincoln relieved McClellan of his command of the Army of the Potomac on November 7, effectively ending the general’s military career.



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