Wednesday, September 10: In Maryland, Federal cavalry informed General George McClellan that General Robert E. Lee’s Confederate Army of Northern Virginia was falling back toward the Monocacy River, away from Frederick. McClellan responded by accelerating his previously sluggish pursuit. As Confederates advanced north in Kentucky, 1,000 “squirrel hunters” volunteered in Cincinnati to defend against a possible Confederate invasion.
Thursday, September 11: In Maryland, Lee’s Confederates entered Hagerstown, and skirmishing with Federal forces increased. Pennsylvania Governor Andrew Curtin called for 50,000 volunteers to defend the state. In Kentucky, Confederates under General Edmund Kirby Smith occupied Maysville. Skirmishing intensified as the Confederates came within seven miles of Cincinnati.
Friday, September 12: In Maryland, McClellan’s Federals reached Frederick as Lee’s Confederates began dispersing in accordance with Special Orders No. 191. “Stonewall” Jackson’s Confederate corps approached Harpers Ferry, and skirmishing took place over the next five days. In Kentucky, Confederates occupied Glasgow as skirmishing continued. The Federal Army of Virginia was officially absorbed into McClellan’s Army of the Potomac. In Pennsylvania, assets and archives were transfered from Harrisburg and Philadelphia to New York. The Confederate Congress debated the wisdom of the northern invasion. President Jefferson Davis wrote to the governors of Texas, Missouri, Louisiana, and Arkansas attempting to assure them that the Trans-Mississippi theater of war was not being ignored.
Saturday, September 13: In Maryland, two Federal soldiers found a copy of Robert E. Lee’s Special Orders No. 191. They were forwarded to George McClellan, who now knew that Lee’s forces were divided. McClellan pushed his Federals west, while Lee learned that McClellan had found his order. Skirmishing intensified. In western Virginia, Federals evacuated Charleston as Confederates under General W.W. Loring advanced from the Kanawha Valley. In New Orleans, General Benjamin Butler, commander of Federal occupation forces, ordered all foreigners to register with Federal authorities.
Sunday, September 14: In Maryland, the left wing of George McClellan’s Federal Army of the Potomac advanced toward Crampton’s Gap to cut off the Confederates at Harpers Ferry and divide Lee’s army. Meanwhile, another Federal force attacked Confederates at South Mountain. After hard fighting, the Confederates withdrew; Federal General Jesse Reno was killed. This became known as the Battle of South Mountain. Meanwhile, “Stonewall” Jackson’s Confederates lay siege to the Federal garrison at Harpers Ferry. In Kentucky, General Braxton Bragg’s Confederates reached Munfordville. Federals under General Don Carlos Buell hurried ahead of Bragg and reached Bowling Green. In Mississippi, a third phase of the overall Confederate offensive began taking shape when Confederates under General Sterling Price occupied Iuka near Corinth.
Monday, September 15: In Virginia (now West Virginia), “Stonewall” Jackson’s Confederates captured Harpers Ferry, taking about 12,000 prisoners. In Maryland, Robert E. Lee’s Confederates at South Mountain fell back to Sharpsburg. Lee was hurriedly concentrating his scattered forces before George McClellan’s Federals could launch a full-scale attack. Lee originally planned to withdraw, but when he learned that Jackson had captured Harpers Ferry, he began forming a line along Antietam Creek. In Kentucky, Edmund Kirby Smith’s Confederates reached Covington across the Ohio River from Cincinnati but quickly withdrew. Braxton Bragg’s Confederates lay siege to Munfordville.
Tuesday, September 16: In Maryland, Robert E. Lee gathered his Army of Northern Virginia and established battle lines along Antietam Creek. “Stonewall” Jackson’s Confederates arrived on the scene after a hard march from Harpers Ferry, while one of Jackson’s divisions under General A.P. Hill remained behind to accept the garrison’s surrender. George McClellan faced criticism for not attacking today. In Kentucky, Bragg continued his siege of 4,000 Federals at Munfordville. Smith’s Confederates withdrew from the Ohio River toward Lexington. President Abraham Lincoln, unable to contact McClellan, wired Governor Curtin of Pennsylvania: “What do you hear from Gen. McClellan’s army?”