- General Robert E. Lee moves north into Maryland with 38,000 Confederate soliders.
- General George B. McClellan has an Union Army of 75,000
- A copy of Lee's plans fall into Union hands and Lee is forced to fight the Union Army near the small town of Sharpsburg
- Lee planned to invade the North, defeat McClellan, march onto Washington, and bring peace and independence to the Confederacy.
- Union troops outnumber Confederate troops 2:1.
- Lee and his troops are forced to face a defensive fight with their backs against the Potomac River.
- A Union victory seemed certain
- The Battle of Antietam was three battles
- Morning of September 17, the Union Army attacks the left flank of the Confederate Army. The battle grows as both sides send in reinfocements. After four hours of battle, neither side have an advantage, and 13,000 men lie dead or wounded.
- Same day, mid-morning, the Union attacked the center of the Confederate line on a long, rutted road. The Confederate Army gives up and retreats. The Union troops do not take advantage and the Confederates hold their line. On the right flank of the Confederate Army, the Union begins to push. After a few tries, the Union Army led by General Ambrose E. Burnside, successfully breakthrough the right flank. The Confederate Army seems to be on the verge of losing.
- On the verge of losing, the Confederate Army is saved when Major General A.P. Hill arrives with backup. This group of Confederate soliders slam into the Union lines pushing them back. As darkness falls, the fighting ends for the day with 4,710 men dead, 18,440 wounded, and 3,043 missing.