The Battle of Antietam was the bloodiest single day in American history. Robert E. Lee raided Maryland after his costly victory during the Seven Days Battles and his masterful victory at Second Bull Run. He had divided his Army of forty thousand men into five parts. Any General more aggressive than George McClellan might have defeated Lee in detail but McClellan was far too cautious. In a twist of fate that could easily be attributed to God a Union Sergeant found a set of Lee's battle plans in an envelope with three cigars. Lee realizing just in time what had happened concentrated his men with his back to the Potomac along Antietam Creek near Sharpsburg Maryland. This revealed the tenacity of Lee and adherence to the Chinese master of war Sun Tzu who said that men fight harder when there is no escape. McClellan had nearly 100,000 men as opposed to Lee's 40,000. Had he attacked all along Lee's lines simultaneously and maintained a constant pressure on all points there is no way that Lee's lines could have held. However McClellan played right into Lee's hands and attacked his left in the East Woods and Farmer Millers cornfield. This allowed Lee to shift troops from other parts of his line to the endangered left flank. Fighting battles this way extended the life of the Confederacy. Not until Ulysses S. Grant took over as overall Union commander in March 1864 would anyone on the Northern side, perhaps with the exception of Lincoln, realize that pressure had to be applied evenly against the numerically inferior Confederate Army. The way to beat them was to deny them the ability to re-enforce threatened points along their lines. Grant would apply this principle in a grand strategy that would encompass both the Eastern and Western theaters simultaneously. These piecemeal attacks at Antietam failed. After the failure of the East Wood attack the fighting spilled over into the West Wood and the area near Dunker Church. When I toured Antietam in 2003 I took this picture from nearly the same angle as the Civil War photographer. The bullets were so thick in Farmer Millers cornfield that the cornstalks were cut completely down.