Antietam – MCA

The Bloodiest Single Day of the American Civil War

HISTORICAL SIGNIFICANCE

The Battle of Antietam is seen as many to be amongst the most defining moments of the American Civil War. Although tactically inconclusive, the Union Army of the Potomac had successfully repelled the Confederate Invasion of Maryland—providing President Lincoln’s administration with the domestic and foreign credibility to issue the Emancipation Proclamation. In issuing this proclamation, Lincoln changed the moral nature of the conflict while formally initiating African American service in the armed forces.

TACTICAL IMPORTANCE

Gen Lee understood the defensive potential offered by the terrain surrounding the town of Sharpsburg, MD. With the Union army bearing down upon him, despite being outnumbered 38,000-87,000, Lee chose to concentrate his forces around three key positions behind the Antietam Creek: the fields and woods North around Dunker Church, the Sunken Road in the center, and the high ground behind Rohrbach Bridge to the South. Rather than ordering a concerted attack against the Confederate position, Union Commander Gen George McClellan committed his force piecemeal in separate assaults from North to South, thus allowing Lee to shift his forces to critical points throughout the day. Despite heavy casualties, the Union morning assault on the area around Dunker’s Church failed to achieve a significant breakthrough. Beginning in midday, the Union army’s repeated assaults against the center of the Confederate position at the Sunken Road eventually achieved a breakthrough; however, McClellan failed to exploit the success with his reserves, and the Confederate line stabilized. The final assault on the Rohrbach Bridge succeeded in almost routing the Confederate army, but after heavy casualties and the timely arrival of Lee’s last reserves, the final assault fell apart. The toll of the day’s fighting was over 21,000 casualties. Ultimately, McClellan failed to break Lee’s lines, and both armies remained on the field until the Confederates withdrew across the Potomac River in the evening of 18 September.

STRATEGIC IMPACT

After his victory at Second Manassas, Gen Robert Lee, commander of the Army of Northern Virginia, seized the strategic initiative to launch an invasion of Maryland with the intent to “liberate” the state, swell his ranks with sympathetic Marylander volunteers, relieve Virginia farmers to complete the late summer harvest, and bring the war to Northern soil. The Confederate invasion achieved initial surprise and successfully captured the Union garrison and supplies at Harpers Ferry; however, Gen McClellan’s Army of the Potomac was able so successfully converge on Lee’s army—defeating his rear guard at the Battle of South Mountain and tempting him into battle at nearby Sharpsburg. Following the battle, despite a brief follow-up skirmish at Shepherdstown, McClellan stalled and allowed Lee’s army to successfully escape back into Virginia. Despite the morale boost produced by the battle in the northern states, McClellan’s inability to follow up his assault on Lee’s crippled army resulted in his removal by the Lincoln administration. While Lee failed to accomplish most of his campaign objectives and lost many of his most seasoned veterans, he was successfully able to maneuver his army back into Virginia to fight another day.

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