September 16, 1862: Gen. McClellan, believing that Lee has nearly 120,000 facing him, is reluctant to move. His troops are arriving along the eastern bank of Antietam creek, just across from the new Confederate lines around Sharpsburg. Somehow, Little Mac gets a notion that Lee is retreating, and trying to get back south into Virginia, even though he simultaneously is preparing to attack Lee. McClellan has 60,000 of his army ready on this date, but does not attack Lee, who has not more than 18,000 troops to oppose the Federals. The intelligence plainly shows that the crossings of Antietam Creek are not difficult or guarded heavily. Yet still he hesitates to move. What McClellan does do is to order Hooker’s I Corps to cross Antietam Creek and to line up for an assault on the Rebel left tomorrow, and thus reveal his hand. Lee shifts troops to his left flank to counter Hooker’s move.