Post Loudoun campaigning sequence.
Assumptions: 9th November setting is as per the previous map
Movement speed for McClellan's troops is eight miles per day (average). They managed twenty miles on the 6th so this seems entirely plausible as an average speed.
Movement speed for Jackson's troops is 16 miles per day along the Valley Pike, ten miles per day otherwise. They were crippled by the same horse problem McClellan had had earlier and Jackson wasn't moving for many days after this, so this seems fairly liberal.
Movement speed for Longstreet's troops is ten miles per day.
Operational assumptions scenario three:
Longstreet will fall back to Gordonsville once McClellan is within a day's march of Culpeper.
Jackson will move on the 12th to join Lee by the shortest possible route and through the Swift Run gap, not pausing to unite his troops first.
Once half of Jackson's wing has joined Longstreet's wing we will pause and assess the situation.
McClellan will advance his main body to Culpeper and then move across the Rapidan, turning then to head to the Fredericksburg area. He will leave one grand division at Orange Court House until the other two are on the road to Fredericksburg.
Forces left at Aldie's Gap and Thoroughfare Gap total to one reinforced division (5,000 effectives) from Siegel's strength.
10th November: McClellan advances his main body in two wings. One moves from Warrenton to the bridge at Waterloo and crosses, the other south to Fayetteville VA. Franklin in the rear wing marches down to Warrenton.
11th November: McClellan advances his right wing from Waterloo to Jefferson VA (now Jeffersonton) and his left wing from Fayetteville to the rail bridge over the North Fork, and crosses the river there. Franklin follows a day behind the right wing.
In two days the left wing has moved about 13 miles plus a river crossing and the right wing has moved about the same distance; they are ready for a faster move the next day and both wings are within about 13 miles of Culpeper.
Longstreet will abandon Culpeper on the 12th; McClellan does not catch him.
12th: McClellan closes on Culpeper from two directions and reaches the outskirts.
Longstreet marches to Cedar Grove and prepares to cross the Rapidan.
Walker marches across the Rapidan.
Jackson begins moving.
Time to reach the Swift Run Gap:
DH Hill is at Front Royal and can either move straight to the Swift Run Gap (52 miles, so 5.2 days to Swift Run) or head to Strasburg (12 miles, so 1.2 days) and then down the Pike to Harrisonburg (48 miles, so 3 days) and then to the Swift Run gap (24 miles, so 2.4 days). Going straight is the superior option.
Jackson is at Winchester, so he's already on the Pike. His trip to Harrisonburg takes about 64 miles, so four days; total time 6.4 days.
AP Hill is just over the Shenandoah from Snickers Gap. His quickest route is to march to Winchester (about 15 miles, so 1.5 days) and then follow the same route Jackson did; total time, 7.9 days.
Once each of Jackson's components reaches Swift Run Gap, it's another 28 miles to Gordonsville (so 2.8 days).
DH Hill will reach Gordonsville at the end of the 19th after eight marches; Jackson will reach Gordonsville early on the 21st after 9.2 marches; AP Hill will reach Gordonsville late on the 22th after 10.7 marches.
13th: McClellan largely rests the majority of his forces as Franklin comes up. His wagons resupply at Culpeper.
Longstreet reaches Gordonsville and is now concentrated.
14th: McClellan marches his forces towards the Rapidan. His right wing makes directly for Rapidan Station, making it eight miles of the 13 miles there.
15th: McClellan's right wing reaches the Rapidan. His left wing reaches Raccoon Ford early in the day and crosses; his centre wing leaves Culpeper following the route of the left wing.
16th: McClellan's right wing reaches Orange Court House. His centre wing reaches Raccoon Ford; his left wing reaches the vicinity of Old Verdierville (modern Rhoadesville).
17th: McClelllan's left wing is on the turnpike road towards Fredericksburg. The route from Old Verdierville to Fredericksburg is about 28 miles and the route from Old Verdierville to Port Royal is 53 miles.
18th: McClellan's centre wing turns onto the turnpike road. His right wing can now disengage from Orange and march east; in reality he would probably leave them in place another day and send the wagons east.
19th: McClellan's right wing marches out of Orange and catches up with the wagons on the turnpike.
n.b. If Jackson moved
immediately (on the 10th) this is when his main body would reach Gordonsville; thus, if Jackson moved immediately there could be a rearguard action along the Orange Turnpike. In this picture of events however Jackson is still not at Gordonsville because of the two-day delay; DH Hill has only just arrived.
20th: McClellan's right wing has marched 24 miles along the turnpike towards Fredericksburg. (this is an average march of 8 miles per day on the 18th, 19th and 20th, most of which was a single long march on the 19th).
Morning of the 21st:
Jackson's men reach Gordonsville. AP Hill still has not arrived.
From Gordonsville to Fredericksburg is 46 miles, while from Orange to Fredericksburg is 37 miles and McClellan's rearguard have already covered 24 of them (they enter Chancellorsville about the same time Jackson reaches Gordonsville).
McClellan's center grand division marched out of Culpeper on the 15th and has marched on the 15th-20th inclusive (six days) so is past Chancellorsville. It could already be in Fredericksburg by this time.
McClellan's left grand division marched out of Culpeper on the 14th and so has had seven days of marching along much the same route.
I would estimate that at this point the left grand division is in Fredericksburg and stretching out to make contact with Port Royal, the right grand division is entering Chancellorsville, and the centre grand division is between the two of them.
I will mark two sets of Confederate positions on the map. The first (orange) is for the "all of the Confederate troops concentrate at Gordonsville" approach I have described; the second (red) is for Lee's historical move to call everyone to the North Anna position. (Distance to reach the North Anna from Gordonsville: ~50 miles, so 5 days, so Longstreet could have reached it on the 18th and DH Hill would be at or past Louisa at the end of the 20th.)
This shows pretty much why Lee gave the orders he did. Jackson was far enough away that he couldn't stop a Union move to Fredericksburg, and if Lee didn't move from Gordonsville until Jackson arrived then the potential is there for McClellan to have the "inside track" to the North Anna position. (The distance to the North Anna from Fredericksburg is about 34 miles; if Longstreet starts marching there from Gordonsville at the same time that a wing of McClellan starts marching there from Fredericksburg, McClellan wins the race.)
The time taken from detaching from the rail line to reach Fredericksburg is in all cases less than one week. This suggests that the movement is plausible because there are some days of "grace" to make contact with Port Royal and obtain supplies, as McClellan could manage a flying column move of ~10 days.
ED: I put DH Hill on the wrong road, he should have been on the next north road alongside the rail line. Mea culpa.
Longest continuous distance marched by a force of McClellan's in this projection is either:
The left GD, which have gone from Warrenton to Culpeper (via a route that means 24 miles in 3 days) then rested a day at Culpeper, then from Culpeper via Raccoon Ford and modern Rhodesville to Fredericksburg (which is another 46 miles), totalling seventy miles from the 10th to the 20th inclusive - eleven days. This means they can reach Fredericksburg quite comfortably even at seven miles per day, let alone eight.
The right GD, which have gone from Warrenton to Culpeper, then rested a day at Culpeper, then from Culpeper via Orange to Chancellorsville. This is the same total distance to within about a mile.
This is quite pleasing, actually!
Bringing the