Battle of Antietam, Maryland – Bloodiest One-Day Battle in American History
The morning of September 17, 1862, dawned shrouded in a dense, clinging fog that permeated the rolling farmland of western Maryland. As soldiers on both sides struggled to clear the dampness from their eyes and equipment, an ominous silence hung in the air, soon to be shattered. Suddenly, the tranquility was ripped apart by the earth-shattering roar of cannons, followed by the staccato crackle of hundreds of rifles. These initial volleys signaled the commencement of the Battle of Antietam, a brutal, twelve-hour struggle that would forever scar the landscape and etch itself into the annals of American history.
The Battle of Antietam stands as a pivotal moment in the American Civil War, not only for its strategic implications but also for its sheer human cost. It was a collision of ideologies and armies, a clash between North and South that reverberated far beyond the fields of Sharpsburg. This single day of carnage would ultimately help pave the way for the emancipation of over four million enslaved African Americans, reshape the political landscape, and leave an indelible mark on the collective American psyche. The Battle of Antietam remains, to this day, the bloodiest single-day battle in American history.
The Battle of Antietam represented the bloody climax of the Maryland Campaign of 1862. Confederate General Robert E. Lee, fresh from a string of victories, boldly led his Army of Northern Virginia across the Potomac River, marking the first major Confederate invasion of the North. Simultaneously, Southern forces were advancing in Kentucky and Missouri, creating a sense of momentum for the Confederacy. Following his decisive victory at the Second Battle of Manassas in late August, Lee recognized the need to maintain the offensive. He wrote to Confederate President Jefferson Davis, emphasizing, "we cannot afford to be idle."
Lee’s strategic objectives were multifaceted. He aimed to achieve a decisive victory on Northern soil, hoping to secure Southern independence and potentially influence the upcoming midterm elections. Furthermore, the invasion aimed to replenish dwindling Confederate supplies, shift the theater of war away from war-ravaged Virginia, and potentially liberate Maryland, a Union state grappling with divided loyalties due to its status as a slave-holding border state.
Upon entering Maryland, Lee made a daring decision, dividing his army to achieve a critical objective: the capture of the Union garrison stationed at Harpers Ferry. This strategic town, nestled at the confluence of the Potomac and Shenandoah Rivers, served as a vital gateway to the Shenandoah Valley and controlled Confederate supply lines. The 12,000 Union troops stationed there posed a significant threat to Lee’s communication and supply routes back to Virginia. Consequently, General Thomas Jonathan "Stonewall" Jackson, with roughly half of the Army of Northern Virginia, was dispatched to seize Harpers Ferry. The remaining Confederate forces marched north and west, towards South Mountain and Hagerstown, Maryland.
In Washington D.C., President Abraham Lincoln, recognizing the gravity of the situation, turned to Major General George B. McClellan to defend the capital and counter Lee’s invasion. McClellan, a meticulous organizer, swiftly reorganized the demoralized Army of the Potomac and began his advance towards the Confederate forces. The two armies first clashed at South Mountain on September 14th. In a series of fierce engagements, Confederate troops attempted to block the Union advance at three key mountain passes – Turner’s Gap, Fox’s Gap, and Crampton’s Gap. Despite putting up a determined resistance, the Confederates were ultimately forced to retreat.
Following the Confederate withdrawal from South Mountain, General Lee initially contemplated a return to Virginia. However, news of General Jackson’s successful capture of Harpers Ferry on September 15th, buoyed his spirits and altered his plans. He made the bold decision to stand and fight at Sharpsburg, a small town nestled along the Antietam Creek.
Lee strategically positioned his forces on the high ground west of Antietam Creek. General James Longstreet’s command occupied the center and right of the Confederate line, while General "Stonewall" Jackson’s men anchored the left. The Hagerstown Turnpike, a crucial north-south artery, provided the Confederates with vital mobility along their line. However, the Potomac River behind them presented a significant risk, offering only one crossing point back to Virginia in case of a retreat. Lee and his men anxiously watched as the Union army amassed on the east side of Antietam Creek, preparing for the impending battle.
Over the course of September 15th and 16th, thousands of Union soldiers marched into position, their movements shrouded by rain and anticipation. General McClellan, known for his cautious approach, meticulously planned his attack. His strategy, as he described it, was to "attack the enemy’s left," and, if "matters looked favorably," to attack the Confederate right, and "whenever either of those flank movements should be successful to advance our center." As the opposing forces positioned themselves during the rainy night of September 16th, a Union soldier from Pennsylvania poignantly recalled, "…all realized that there was ugly business and plenty of it just ahead."
The Battle of Antietam, a twelve-hour maelstrom of violence, commenced at dawn on September 17, 1862. The fighting can be broadly divided into three distinct phases, each characterized by intense combat and staggering casualties. The initial phase involved a series of three major Union assaults against the Confederate left flank, unfolding over a period of seven grueling hours. General Joseph Hooker’s command spearheaded the first Union assault, followed by attacks from General Joseph Mansfield’s and General Edwin Sumner’s troops. McClellan’s initial plan quickly unraveled into a series of uncoordinated Union advances, each met with fierce Confederate resistance. The fighting was especially brutal in areas that would become infamous: the Cornfield, the East Woods, the West Woods, and the Sunken Road. General Lee skillfully shifted his troops to meet each Union thrust, resulting in savage, close-quarters combat. After eight hours of relentless fighting, the Confederates were pushed back, but their line remained unbroken. By the end of this phase, over 15,000 soldiers lay dead or wounded.
While the Union assaults raged on the Sunken Road, approximately a mile and a half to the south, Union General Ambrose Burnside initiated an attack on the Confederate right. Burnside’s primary objective was to capture the bridge that would later bear his name. A small but determined Confederate force, positioned on higher ground, managed to delay Burnside’s advance for a critical three hours. The bridge was finally taken around 1:00 p.m., but Burnside then spent two hours reorganizing his troops before resuming the advance – a delay that would prove costly. The Union advance finally began, only to be met by the arrival of Confederate General A.P. Hill’s reinforcements, who had marched from Harpers Ferry. Hill’s timely arrival shattered the Union attack, turning back Burnside’s troops.
Neither flank of the Confederate army yielded sufficiently to allow McClellan to launch a decisive attack with his center, leaving a significant portion of the Union army uncommitted to the battle. Despite the horrific casualties – over 23,000 men killed, wounded, or missing out of nearly 100,000 engaged – both armies stubbornly held their ground as the sun began to set on the ravaged landscape. On September 18, 1862, the opposing armies focused on tending to their wounded and burying their dead. Under the cover of darkness, General Robert E. Lee’s army retreated back across the Potomac River to Virginia, effectively ending his first invasion of the North.
Lee’s retreat provided President Abraham Lincoln with the opportunity he had been waiting for: to issue the preliminary Emancipation Proclamation. This pivotal document, announced just days after the Battle of Antietam, declared that all slaves in Confederate-held territory would be freed, effective January 1, 1863. The Civil War, initially fought to preserve the Union, now had a dual purpose: to preserve the Union and to end slavery.
The Battle of Antietam was indeed the bloodiest single-day battle in American history. In the end, an estimated 23,100 casualties were suffered, a staggering testament to the ferocity of the fighting and the devastating impact of the Civil War.
Today, the Antietam National Battlefield Site, managed by the National Park Service, stands as a solemn reminder of the sacrifices made on that fateful day. The site offers visitors a range of opportunities to learn about the battle and its significance. The Visitor’s Center provides access to films and documentaries that bring the battle to life. Visitors can explore the battlefield on a self-guided 8 ½ mile auto tour with 11 stops, embark on self-guided hikes, or participate in Ranger-led talks and walks.
The Antietam National Battlefield Site was established on August 30, 1890, with the purpose of commemorating the events of September 17, 1862, and preserving the battlefield’s key features. Originally administered by the War Department, the site was transferred to the U.S. Department of the Interior in 1933 and placed under the management of the National Park Service.
The Battle of Antietam unfolded over an area of approximately 12 square miles. The site currently encompasses 184 acres and includes approximately 5 miles of paved avenues. Numerous monuments, markers, and narrative tablets are strategically placed along the battlefield avenues, marking the positions of infantry, artillery, and cavalry units. Similar markers detail the actions that occurred at Turner’s Gap, Harpers Ferry, and Blackford’s Ford. Key artillery positions are marked by cannons, and ten large-scale field exhibits illustrate troop positions and battle action at critical points on the field.
The Antietam National Cemetery, located on the eastern edge of Sharpsburg, serves as the final resting place for Federal soldiers who perished in the Battles of Antietam, South Mountain, and other minor engagements in the region. Of the 4,773 Civil War burials, 1,836 are listed as unidentified, a poignant reminder of the anonymity of death in war.