Today, we are pleased to welcome guest author Kevin Pawlak
Fortunately, for the sake of debate, the outcome of Civil War battles is not as clear-cut as that of a football game, where one can look at the scoreboard at the end of the game and easily determine who won, who lost, or, in some cases, if the outcome was a draw. Historians endlessly debate whether certain battles were overwhelming victories, marginal victories, or draws. Perhaps no other battle’s tactical outcome is more misunderstood than the bloodiest single day battle of the war: Antietam.
No one would doubt Antietam’s significance in the larger picture of the war. However, the common conception of Antietam is that the battle was tactically a draw, with neither side having gained a significant enough of an advantage to have claimed the victory. This article will challenge that commonly held belief, using particular instances from the battle and the Maryland Campaign to demonstrate the Army of the Potomac’s victory at Antietam.
The morning following the Battle of Antietam, Major General George B. McClellan wrote his wife regarding the previous day’s action:
We fought yesterday a terrible battle against the entire rebel army. The battle continued fourteen hours and was terrific; the fighting on both sides was superb. The general result was in our favor; that is to say, we gained a great deal of ground and held it. It was a success, but whether a decided victory depends upon what occurs to-day. I hope that God has given us a great success.
Most people automatically dismiss McClellan’s proclamation of marginal victory as farcical. But in order to gauge McClellan’s and the Army of the Potomac’s success at Antietam, we must go back to the day before the battle, when the Federal army gathered on the east side of Antietam Creek opposite their enemy.
Robert E. Lee and his Confederate army felt safely ensconced in their position on the west side of the Antietam. Following his defeat at South Mountain on September 14, Lee abandoned his campaign and made plans for his army to vacate Maryland. As Lee crossed the Antietam and ascended an impressive incline between the creek and Sharpsburg, his confidence began to build. News soon arrived that his divided army, now free to unite, could do just that and Lee determined to salvage his campaign. Examining the ridge he perched his men atop, Lee told his soldiers, “We will make our stand on these hills.”
Much has been made of the body of water behind the Army of Northern Virginia on September 17—the Potomac River. In fact, its presence and Lee’s decision to stand and fight at Sharpsburg is one of the most criticized of his military career (Lee was not pinned directly against the river as some believe, but in fact had a series of ridges to fall back on closer to the river and also had several miles of open countryside behind his lines which he used to move his troops skillfully to threatened points of the battlefield on September 17). While Lee may have momentarily considered the minor dangers of fighting with the Potomac several miles behind him, he probably did so only briefly as he looked east from his position and saw another body of water which he would usher into his defense.
Throughout the Maryland Campaign, Robert E. Lee always moved with a natural barrier between his army and the enemy. The first was the Potomac River, which Lee crossed to enter Maryland at the outset of the campaign—a time when many Federals in the area were on the south side. Next, while Lee rested his army in Frederick for several days, the Monocacy River served as a buffer between the two forces. Third, when Lee divided his army to subdue the Union garrisons in the Shenandoah Valley, he placed Catoctin and South Mountains between his separated army and McClellan’s forces. When McClellan pierced that barrier on September 14, Lee sought another barrier to shelter behind; he found Antietam Creek.
Attacking across a formidable stream like the Antietam would be no easy task and both McClellan and Lee knew that well. In his final report of the campaign, McClellan called Lee’s position atop a high ridge behind a creek “one of the strongest to be found in this region of country, which is well adapted to defensive warfare.” After determining the best way to attack Lee, McClellan, the general often portrayed as one who shied from a fight, attacked despite the obvious strength of the Confederate position.
In the vicinity of what became the Antietam battlefield, there are five major crossings of the creek, named in order from north to south: the Upper Bridge, Pry’s Ford, the Middle Bridge, the Lower (Burnside) Bridge, and Snavely’s Ford. When McClellan ordered his army forward on the afternoon of September 16, 1862, only one of those crossings was securely in his hands: the Middle Bridge. Joseph Hooker’s crossing at the Pry’s Ford and Upper Bridge placed those two crossings squarely under Federal control, but Lee still held the crossings on the southern end of the field. Why did Lee cede the battlefield’s northern crossings to McClellan? The answer may never be known with certainty, but a study of Lee’s generalship throughout the campaign and war may provide a clue.
Lee’s decision to not directly defend the upper crossings may have both defensive and offensive reasons behind it. Firstly, Lee recognized the weakness of the area where his left flank would be anchored during the coming fight—its defensibility paled in comparison to that found in the center and right of Lee’s line. His left flank had to be anchored back from the creek in order to keep the road north, the Hagerstown Pike, within his control should he decide to move in that direction. Additionally, by baiting the Federals to cross the creek, Lee might be able to catch it in a position where the enemy army found itself on two sides of a formidable stream, something he took advantage of several months earlier outside of Richmond and something he would try again along the banks of the North Anna River in 1864.
Robert E. Lee’s strategy on September 17 was not merely to counter the blows of the Union army but, according to some historians, Lee prepared offensive strikes meant to drive the Federals back across Antietam Creek and destroy large portions of the Army of the Potomac. If those offensive strikes were successful, Lee could regain some of the upper crossings of Antietam Creek for the Army of Northern Virginia and, in turn, catch the Army of the Potomac divided by the creek with portions of that army fighting with the wide stream at its rear. Unfortunately for Lee, McClellan blunted those assaults and did not give Lee the opportunity for sweeping success he desired.
When viewing the terrain of the Antietam battlefield, George McClellan—like Lee—determined the weaker part of the line to be the northern half. Thus, he decided to open his attacks on September 17 there, using the aggressive Joseph Hooker as the tip of the spear. George McClellan never left a solid answer regarding what his plans for that day were but, based off of his two reports of the campaign, which occasionally differ, and the reports of his subordinates, a reasonable guess can be determined as to what McClellan instructed his army to do.
Despite the discrepancies between McClellan’s October 1862 and August 1863 reports, one thing seems clear: he aimed to maintain as much flexibility as possible during the fight so he could react to the flow of battle. Regardless, he plotted out his course of action and determined to first strike Lee where he believed Lee was weakest—the northern half of the battlefield. Meanwhile, Burnside would attempt to roll up the Confederate right should Hooker prove successful in drawing the enemy away from that sector of the field. McClellan believed that one or both of these attacks could be successful without drawing much from his reserves. Should he have enough reserves at the moment he felt the Confederates pressured the most, he would send them directly against the heights in his front.
These attacks did not go precisely as McClellan had hoped and the ferocious fighting on September 17 forced McClellan to send his reserves away from the center of his line. Though his plan did not come to full fruition, his army had gained ground compared to what they held at the start of the fight.
Even though the ground that the Army of the Potomac had gained proved minimal in some parts of the field—approximately one-half mile in most parts—the elimination of the buffer between the two armies forced Lee’s hand: he had to seek another barrier. For Lee, the only one left was the Potomac River several miles behind him. However, he could not pull out of his position immediately and had to wait until the night of September 18 to do so. Lee not being driven from the battlefield the day of the battle has, just like the argument that the Army of the Potomac gained little ground, been used by many students of the war to justify their stance that the Battle of Antietam was a drawn fight. Upon closer examination, this too falls apart.
Lee’s stand at Sharpsburg on September 18 is something visitors to Antietam battlefield sometimes equate to the southern chieftain holding his fist defiantly in the air, daring McClellan to attack him. In reality, Lee likely stood there on the 18th because, as one of the campaign’s leading historians put it, “there was good cause to believe that waiting a day could not lead to a disaster worse than attempting a hasty retreat.” No preparations had been made for a withdrawal on September 17 “and to locate the troops after the day’s confused fighting and to organize their withdrawal in darkness may have been impossible.” Evidence also suggests that Lee began removing some of his important assets—particularly his wounded—to the Virginia side of the Potomac on the night of September 17, implying serious considerations of a return to Virginia as soon as it was practicable for the army to do so.
George McClellan originally planned to continue the attack on September 18 but eventually decided against it before anyone moved forward. Simply put, he did not foresee any better chance at defeating the enemy thanks to what he had seen the previous day (every attack he had thrown at Lee had been equally repulsed). Additionally, the Army of the Potomac was exhausted, worn out, and bled out from corps commander to private (McClellan could count three corps commanders, four division commanders, and ten brigade commanders as casualties in the campaign as well as over 12,000 others), thus seriously diminishing the likelihood of destroying Lee’s forces if any of the troops who fought on September 17 were to be reused.
Lastly, though McClellan did have some relatively fresh troops available on September 18, those fresh troops only equaled the number of men Lee had within his entire army. Historian Joseph Harsh said it best: “There are no good grounds—even in hindsight—for believing the 24,000 men in the Fifth and Sixth Corps (including Couch) could have defeated, let alone destroyed, Lee’s 25,000.” Armchair generals love to berate McClellan for not attacking again despite these severe handicaps but always fail to recognize that he did not back down on September 18, thus “exert[ing] enough pressure” on Lee to force him to abandon his position around Sharpsburg. And when Lee and his army did leave Maryland, they did so in one night; it took them three days to enter the Old Line State. Lee and the Army of Northern Virginia left in a hurry.
The Army of Northern Virginia that returned to Virginia on September 18-19 was not the one Lee brought with him into Maryland just a couple of weeks earlier. Lee lost nearly 14,000 men in battle from September 5-20, and he estimated the number of stragglers who left the army’s ranks as anywhere “from a third to one-half of the original numbers” the army began the campaign with. At Antietam alone, Lee lost an estimated 27.62% of his men compared to 22.16% of the Army of the Potomac. The arithmetic that heavily plagued the Confederacy later in the war was already counting heavily against it.
Army of the Potomac records counted 13 guns, 39 colors, at least 15,000 small arms and 6,000 prisoners as the booty they reaped from the campaign. Clearly, the Army of Northern Virginia had received a beating at the hands of George McClellan and the Federal army. One other historian studying Lee’s generalship claimed Antietam “momentarily paralyzed” the Army of Northern Virginia, which “never fully recovered” from that fight.
Thus, the pounding, relentless blows that McClellan threw at Lee’s army all day on September 17 had their effect. The assaults forced the crossing of Antietam Creek, seized crucial crossing points critical to the retention of Lee’s defensive position, and ultimately forced Lee to seek another defensive barrier, which left him with no other option than to leave Maryland for the safer soil of Virginia. These assaults also did gain critical high ground on the northern end of Lee’s line all the while exacting a fearsome toll on the Confederate army, which proportionately got the worst of the fight. Lee’s army would feel that fight for a long time beyond September 17, 1862, and the misfortune and defeat that they suffered on the banks of the Antietam would leave a bad taste in their mouths for many months. Indeed, George McClellan was correct—the result of that bloody fight at Antietam was in his favor, and he had the trophies to prove it.
 George B. McClellan, McClellan’s Own Story (New York: Charles L. Webster & Company, 1887), 612.
 Joseph L. Harsh, Taken at the Flood: Robert E. Lee & Confederate Strategy in the Maryland Campaign of September 1862 (Kent, OH: The Kent State University Press, 1999), 305.
 Edward Porter Alexander, Fighting for the Confederacy: The Personal Recollections of General Edward Porter Alexander, ed. Gary W. Gallagher (Chapel Hill, NC: The University of North Carolina Press, 1989), 145-46. E.P. Alexander was one of Lee’s staunchest critics regarding his decision to fight at Sharpsburg, a decision Alexander called Lee’s “greatest military blunder…”
 OR vol. 19, pt. 1, 54.
 Harsh, Taken at the Flood, 303-04.
 See the provocative article, Steven W. Knott, “Lee at Antietam: Strategic Imperatives, the Tyranny of Arithmetic, and a Trap Not Sprung,” Army History no. 95 (Spring 2015): 32-40, for an excellent example of this theory.
 OR 19, pt. 1, 30, 55.
 Ground gained, or lack thereof, is often used by historians as a gauge to determine the victor of Civil War battles. However, that seems negligible. Most would agree that the Battle of Gettysburg was a Union victory but Lee gained much more ground than the Union Army ever did.
 Harsh, Taken at the Flood, 428.
 Kevin R. Pawlak, Shepherdstown in the Civil War: One Vast Confederate Hospital (Charleston, SC: The History Press, 2015), 87.
 Harsh, Taken at the Flood, 444.
 Joseph L. Harsh, Sounding the Shallows: A Confederate Companion for the Maryland Campaign of 1862 (Kent, OH: The Kent State University Press, 2000), 222; OR vol. 19, pt. 2, 606.
 Ezra A. Carman, The Maryland Campaign of September 1862, ed. Thomas G. Clemens, vol. 2, Antietam (El Dorado Hills, CA: Savas Beatie, 2012), 602-11.
 OR vol. 19, pt. 1, 33.
 Quoted in Alan T. Nolan, “General Lee,” in Lee the Soldier, ed. Gary W. Gallagher (Lincoln, NE: University of Nebraska Press, 1996), 245.