These five words were the ones most frequently used by Lincoln as he sent telegraph messages to General McClellan. There were days in which McClellan did not respond for hours, and the president continued to send the same message. If McClellan or Robert E. Lee had been able to see the Maryland campaign from the air, this is what either one would have reported.

The Confederate Army of Northern Virginia was entirely on the Maryland side of the Potomac, but it was split into three sections, two of which were besieging Harpers Ferry. Smoke was rising from the Ferry, which had already changed hands twice in the war, and was about to do so a third time. Six corps of the Army of the Potomac were converging on two mountain passes: Crampton’s Gap and Turner’s Gap. Beyond them lay the central part of the Army of Northern Virginia, at this point only 25,000 strong. A foot race had commenced the day before. The Army of the Potomac was attempting to catch and destroy the Army of Northern Virginia in pieces; Lee, for his part, recognized the danger and was calling in his outposts.