Today marks the 150th anniversary of the Battle of Antietam, the bloodiest day of the Civil War and one of the most important military operations of the conflict. The battle forced Confederate Gen. Robert E. Lee to retreat back to Southern soil, giving a timely boost to Northern morale and emboldening President Abraham Lincoln to issue the preliminary Emancipation Proclamation announcing his decision to free the slaves in areas of rebellion.
The Battle of Antietam stamp features a reproduction of an 1887 painting by Thure de Thulstrup. The painting was one of a series of popular prints commissioned in the 1880s by Boston publisher Louis Prang & Co. to commemorate the Civil War.
During the summer of 1862, Confederate forces rebounded from a series of setbacks that had them teetering on the edge of defeat earlier in the year. The South’s victory in Northern Virginia at Second Bull Run, in late August, especially reversed the tide of the war. Whereas earlier Union Gen. George B. McClellan and his Army of the Potomac seemed poised to strike at the Confederacy’s capital at Richmond, Virginia, now Confederate Gen. Robert E. Lee and his Army of Northern Virginia were on the offensive.
In early September, Lee decided to build on the momentum of Second Bull Run by invading the North. A victory in Maryland, where he hoped to rally southern sympathizers to his side, might finally convince Britain and France to recognize the Confederate States of America.
To prevent such a calamity, President Abraham Lincoln ordered McClellan to pursue Lee after his army crossed the Potomac River into Maryland. Lincoln saw an opportunity to take advantage of Lee’s vulnerability as his army moved away from its home base. With superior numbers and the good fortune of obtaining a copy of Lee’s strategic plans, McClellan had advantages that gave Lee pause. But Lee was reluctant to retreat, and—bolstered by news that Confederate General Thomas “Stonewall” Jackson had captured Harpers Ferry—decided to confront McClellan and concentrate his forces along the banks of Antietam Creek, near Sharpsburg, Maryland. It was this fateful decision that led to the bloodiest day of the Civil War, on September 17, 1862.
The Battle of Antietam began at dawn, with Union troops outnumbering the Confederates by two to one. The ever-cautious McClellan believed, however, that his forces were outnumbered, so he kept a large number of troops in reserve. He attacked Lee’s forces piecemeal rather than all at once, allowing Lee to shift troops around to meet the different threats. Union soldiers were attacking the right flank of Lee’s army late in the afternoon when Confederate reinforcements arrived from Harpers Ferry and mounted a counterattack. With more than a quarter of his troops killed or wounded in the battle, Lee withdrew from the field and retreated to Virginia during the night of September 18.
The soldiers on both sides were said to have fought like there was no tomorrow, in settings later memorialized as Bloody Lane, the Cornfield, and Burnside’s Bridge. Photographer Mathew Brady vividly captured and exhibited the gruesome consequences of the battle. As the New York Times reported, “Mr. Brady has done something to bring home to us the terrible reality and earnestness of war. If he has not brought bodies and laid them in our door-yards and along the streets, he has done something very like it.”
Although the Union victory was limited—McClellan failed to pursue and crush Lee’s troops as they retreated—the Battle of Antietam was one of the most important military operations of the Civil War. Aside from forestalling foreign recognition of the Confederate states, the battle gave a tremendous boost to Northern morale. The New York Times, for example, exulted that September 17 would “hereafter be looked upon as an epoch in the history of the rebellion, from which will date the inauguration of its downfall.”
The Battle of Antietam stamp was issued earlier this year, along with a stamp depicting the Battle of New Orleans, as part of a series commemorating the 150th anniversary of the Civil War, which engulfed the nation from 1861 to 1865. A souvenir sheet of two stamp designs is being issued through 2015 for each year of the war.