It is 4 September, 1862. Confederate General Robert E. Lee, still flush from his smashing victory over Union forces at the Second Battle of Bull Run on 30 August, has moved the Army of Northern Virginia west from Bull Run to White’s Ford, where men and horses can easily cross the Potomac River. Lee has an ambitious plan: invade Maryland, a state that voted in 1861 not to secede, but is a state where slavery is legal. The site of Lee’s invasion will carry his army into western Maryland and possibly into Pennsylvania, where Lee hopes to cut the rail lines that link the Union capital city of Washington with the mid Atlantic states. Lee is also hoping that an invasion of Union territory with his unbeatable Army of Northern Virginia will have an effect on the coming midterm elections. Union sentiment for continuing the war is wearing thin. With the exception of casualty lists, the Union Army of the Potomac has very little to show for its efforts. Generals McDowell, McClellan, and Pope have all been bested by Lee, despite superior numbers of men on the Union side. Lee is hoping that an invasion will help to elect more Copperhead Democrats in November. The Copperhead faction of the Democratic party consists of men who feel that it’s time to reach a negotiated settlement with the Confederacy and to end the war.
While the Union Army of the Potomac is battered from its defeat at Second Bull Run, it is in better combat shape than the Army of Northern Virginia. General Pope, who commanded the Union forces at Bull Run, didn’t commit all of his divisions during that disaster, so there are fresh formations ready for combat. More forces are also pouring into Washington so that the capital city can be adequately defended should Lee wheel and try to take the city from the rear. The greatest advantage the Union Army has is an abundant source of supplies, particularly food and ammunition. So far all of the combat in the war has taken place in Virginia, and with two armies living and fighting off the land, vital supplies in that state are becoming scarce.
The invasion of Maryland was Lee’s idea. He came up with the plan and submitted it to Confederate president Jefferson Davis, who had served as Secretary of War in the Franklin Pierce administration. Davis gave his assent to Lee’s bold move, so on 4 September, 1862, the invasion began with the crossing of the Potomac River.
While the invasion looked sound on paper, reality always has a way of intruding in wartime, particularly in a civil war, and particularly with regards to the Confederate States of America. These 11 states were fighting to break away from the Union, not to overthrow the Union government. In short, they were rebelling. Standard rebellion tactics call for those in rebellion to make the government come to them, not to take the fight to the government. By invading Federal territory Lee placed his army in significant danger, while at the same time leaving the territory of Virginia largely undefended. Lee also made an extremely risky move by detaching Stonewall Jackson’s division from the main force and sending it further westward to capture the Federal arsenal at Harpers Ferry.
What if Lee had stayed put in Virginia after his victory at Second Bull Run, established strong defensive positions, and waited out the Union Army?
This is one of the more tantalizing what ifs in history. While President Lincoln was determined to keep the Union together, he was the leader of a dwindling band of believers. Lincoln was also dealing with a problem that would haunt him and the war effort until 1864: bad generals. He had fired General McClellan after his disastrous Peninsula campaign in the spring of 1862, and now he was facing the need to fire General Pope for his defeat at Second Bull Run. Before he could even begin planning for an assault on Lee’s forces, he would have to find a commander who had the skill and bravery to take on this unbeatable foe. That would take time, time that would give Lee room to fortify and replenish. It would also force the Union to plan for an invasion of Virginia while at the same time keeping enough troops on hand to defend Washington from attack. Confederate troops could easily move across the Potomac at any time and strike the city from the rear. The sight of Confederate troops in the streets of Washington would be a devastating blow to Union morale, which was already at a nadir. Enemy troops in the streets of the capital city could also spur France, the United Kingdom, and other European powers to recognize the Confederate government and to challenge the Union blockade of southern port cities. Lincoln was well aware that some European countries were eagerly hoping for the complete break up of the United States, as this would open up more North American territory to colonization and empire.
Lee’s invasion, while satisfying his ego as an unbeaten general, would prove to be an epic mistake, for it would transform the war. The invasion of Union territory gave President Lincoln the impetus he needed to expand the goal of the war beyond preserving the Union. Invading a state that hadn’t seceded gave Lincoln the moral high ground to denounce the Confederacy as coming into existence simply to extend slavery beyond its borders. Lincoln, who had reluctantly re-appointed General George McClellan as commander of the Army of the Potomac on 2 September, 1862, hoped that the more powerful Union Army would destroy Lee’s forces. A significant Union victory would put power behind Lincoln’s plans to use an Executive Order to free the slaves in Confederacy. The coming Emancipation Proclamation would declare all slaves in rebelling states to be free as of 1 January, 1863. A crushing defeat, combined with the threat of emancipation in four months would, in Lincoln’s hopes, force the Confederates to cease combat and negotiate an end to the rebellion.