On September 4, 1862 General Robert E. Lee crossed the Potomac into Maryland with 40,000 picked troops. He was confident of victory. The outcome would surprise everyone.

Due to the lost orders of General Lee, the Union Army was aware of his plans. Word got back to Lee and he knew he had to move quickly.

On September 16 General George B. McClellan confronted Lee's army of northern Virginia at Sharpsburg, Maryland.

At dawn on September 17 General Hooker's Corps mounted a powerful assault on Lee's left flank.

The confederate army was still greatly outnumbered. This began the single bloodiest day in American military history.

Attacks and counterattacks swept across Millers cornfield and fighting swirled around Dunker Church. The Union assaults against the sunken road (later known as Bloody Lane) eventually pierced through the Confederate center. The Federal advantage was not followed up.

Later in the day, General Burnside's corps got in to action, crossing the stone bridge over Antietam Creek (later known as Burnside Bridge) and rolling up the Confederate right. Nobody knows exactly what happened at the bridge yet it is known that at a crucial moment General A. P. Hill's division arrived from Harpers Ferry and counter attacked, driving Burnside back.

Although outnumbered two-to-one, Lee committed his entire force, while McClellan sent in less than three-quarters of his army. In spite of crippling casualties Lee continued to skirmish with McClellan throughout the 18th.

After dark, Lee ordered his battered army to withdraw across the Potomac into the Shenandoah Valley.

The result of the battle: Well, that's any one's call. Yet when it comes to strategy, it's definitely the North's win.