P.S. as a matter of curiousity, when Meade finalyu got around to bridging the Potomac, does anyone know how long it took him to actually get the AoP across. I ask this because when McClellan Finally got around to crossing the Potomac, I understand it still took almost a week to cross the same river that Lee crossed in a day.
As previously posted, it took a day to construct the first bridge. at Berlin, which was either 1500+ feet or 1700+ feet (I've seen both used). The 2nd bridge at Berlin (which looks like it is perhaps 100 yards away in the photo) took longer to finish, probably because they had insufficient material to complete it. The Engineers scavanged material wherever they could find it to do the job -- including raising damaged pontoons from earlier operations off the bed of the Potomac so they could repair them with wood from cracker boxes.
Using these two bridges, it took the AoP about 4 days and nights to cross the bulk of the troops, using both bridges and crossing constantly. Once Lee had moved off, they also started repairing the bridge at Harpers Ferry (badly damaged by a Union raid on the 5th, in use by the Confederates before then).
Tim