Lee made the decision to invade the North in September 1862. The campaign was not two weeks old before overambitious plans and a lost set of orders forced a tired and outnumbered Army of Northern Virginia to fight for its very existence along Antietam Creek.
Within days of Lee's triumph at the Second Manassas on August 30, he had worked out a way to capitalize on his success. He would take the Army of Northern Virginia north, through Maryland, picking up supplies and recruits on the way, into Pennsylvania. This would have the result of encouraging pro-Southern Marylanders, while attracting the Union forces away from Virginia. Farmers in the state would have time to work their fields free from marauding soldiers, while Lee's army made Northern farmers take some of the brunt of the war. Indeed, food was now a major concern, whether he stayed in Virginia waiting to react to another Union blow against Richmond, which was sure to come, or if he moved north to subsist off the land there. Moreover, once on Northern soil, he could maneuver on open ground, something his army excelled at, rather than be held to defensive lines.
There was also another consideration, and that was political. If Union forces were defeated decisively on Northern soil, European powers, especially Britain and France, could well be persuaded to recognize the South's independence. With that kind of international recognition as its base, the South might well be able to negotiate a peace. It was a gamble that Lee felt was worth taking.
On September 4 he started his force of some 55,000 across the Potomac River at White's Ford just above Leesburg, Virginia. The army was not in the best of