Dawn approached slowly through the fog on September 17, 1862. As soldiers tried to wipe away the dampness, cannons began to roar and sheets of flame burst forth from hundreds of rifles, opening a twelve hour tempest that swept across the rolling farm fields in western Maryland. A clash between North and South that changed the course of the Civil War, helped free over four million Americans, devastated Sharpsburg, MD, and still ranks as the bloodiest one-day battle in American history.
The Battle of Antietam was the culmination of the Maryland Campaign of 1862, the first invasion of the North by Confederate General Robert E. Lee and the Army of Northern Virginia. In Kentucky and Missouri, Southern armies were also advancing as the tide of war flowed north.
After his dramatic victory at the Second Battle of Manassas during the last two days of August, General Robert E. Lee wrote to Confederate President Jefferson Davis that “we cannot afford to be idle.” Lee wanted to keep the offensive and secure Southern independence through victory in the North. Lee knew that a northern campaign could influence the fall mid-term elections; help his army obtain much needed supplies; move the war out of Virginia, possibly into Pennsylvania; and liberate Maryland, a slave-holding Union state with divided loyalties.
Arriving in Frederick, MD, after crossing the Potomac River, Lee boldly divided his army to capture the Union garrison stationed at Harpers Ferry, the gateway to the Shenandoah Valley. The 12,000 Union soldiers stationed there were a threat to Lee’s supply and communication lines, so Lee sent General Thomas “Stonewall” Jackson and about half of the army to capture Harpers Ferry. The rest of the Confederates moved north and west toward South Mountain and Hagerstown, MD.
Back in Washington, President Lincoln turned to Major General George B. McClellan to protect the capital and respond to the invasion. McClellan quickly reorganized the demoralized Army of the Potomac and advanced towards Lee.
The armies first clashed on South Mountain on September 14 where the Confederates unsuccessfully attempted to hold three mountain passes – Turner’s, Fox’s and Crampton’s Gaps. As the Confederates retreated from South Mountain, Lee considered returning to Virginia. However, upon hearing that Stonewall Jackson had captured Harpers Ferry on September 15 Lee decided to make a stand at Sharpsburg, MD.
Lee gathered his forces on the high ground west of Antietam Creek. General James Longstreet’s command held the center and the right of the Confederate line while Stonewall Jackson’s men filled in on the left. With the Hagerstown Pike running north and south along Lee’s line he had the advantage of mobility, however with the Potomac River’s only crossing to his rear he also ran the risk of entrapment. Lee and his men watched the Union army gather on the east side of the Antietam. Thousands of soldiers in blue marched into position throughout the 15th and 16th as McClellan prepared for his attempt to drive Lee from Maryland.
McClellan’s plan was, in his words, to “attack the enemy’s left,” and when “matters looked favorably,” attack the Confederate right, and “whenever either of those flank movements should be successful to advance our center.” As the opposing forces moved into position during the rainy night of September 16, one Pennsylvanian remembered, “…all realized that there was ugly business and plenty of it just ahead.”
The twelve hour battle began at dawn on the 17th. For the next seven hours there were three major Union attacks on the Confederate left, moving from north to south. General Joseph Hooker’s command led the first Union assault. Then General Joseph Mansfield’s soldiers attacked, followed by General Edwin Sumner’s men as McClellan’s plan broke down into a series of uncoordinated Union advances. Savage combat raged across the Cornfield, East Woods, West Woods and the Sunken Road as Lee shifted his men to withstand each of the Union thrusts. In just over eight hours 15,000 soldiers were killed or wounded.
While the Union troops assaulted the Sunken Road, Union General Ambrose Burnside attacked the Confederate right flank a mile-and-a-half farther south. His first task was to capture the bridge that would later bear his name, but a small Confederate force on the high ground held the bridge for three hours. After taking the bridge at about 1:00 PM, Burnside spent two hours reorganizing his forces before resuming the attack. The delay proved critical: Confederate reinforcements arrived from Harpers Ferry and Burnside was turned back. Ultimately the Confederate flanks held enough so that McClellan never ordered his forces in the center to attack. As a result a sizable element of the Union army never entered the battle.
Of the nearly 100,000 Soldiers on both sides, 23,000 were killed or wounded on that day, yet both armies stubbornly held their ground as the sun set on the devastated landscape. The next day, September 18, the opposing armies gathered their wounded and buried their dead. That night Lee withdrew back across the Potomac to Virginia, ending his first invasion of the North.
Source
Article Courtesy of the National Park Service
http://www.nps.gov/anti/historyculture/upload/Battle%20history.pdf