Early September 1862 .
Meanwhile in one of the greatest intelligence coups of the war, two Federal.
To capture the Union garrison at Harpers Ferry, the Confederate commander boldly divides his army.
Lee decides on a daring course of action.
McClellan\'s Army of the Potomac moves northwest through Maryland in pursuit of the Confederates.
George B.
Gen.
Maj.
Lee\'s Army of Northern Virginia crosses the Potomac River and invades the North for the first time during the Civil War.
Robert E.
Gen. . .
Early September 1862