the invasion failed to march much beyond their jumping off points. American forces won several notable successes later in the war, restoring their position along the border, but never effectively threatened British Canada.

The failure of the invasion turned what Americans had imagined as an easy, lucrative offensive war into a defensive struggle. It dealt a major setback to the vision, cherished by Americans, of a North America completely under the domination of the United States. Britain would hold its position on the continent, eventually ensuring the independence of Canada from Washington.

Battle of Antietam

In September 1862, Robert E. Lee invaded Maryland with the Army of Northern Virginia. Lee’s objectives were to take advantage of foraging opportunities (the movement of armies across Virginia had left the terrain devastated), support arevolt in Maryland and potentially inflict a serious defeat on Union forces. Unfortunately for Lee, information about his battle disposition fell into the hands of General George McClellan, who moved to intercept with the much larger Army of the Potomac. President Lincoln saw this as an opportunity to either destroy or badly maul Lee’s army.

The Battle of Antietam resulted in 22,000 casualties, making it the bloodiest day in the history of the Americas. Despite massive numbers, a good working knowledge of Lee’s dispositions and a positional advantage, McClellan failed to inflict a serious defeat on the Confederates. Lee was able to withdraw in good order, suffering higher proportional casualties, but maintaining the integrity of his force and its ability to retreat safely into Confederate territory.

McClellan probably could not