Here's an outline with maps of the operational moves. The maps are based on the GCACW game maps, which show the little roads and terrain pretty well.
Operational movements:
24th October (i.e. before the campaign itself starts)
I've co-located DH Hill and Walker because I have no better information about their exact configurations.
At this point both armies are in a defensive posture for the most part, along the upper Potomac. McClellan is spread out firstly because his intent up to this point was to strike into the Shenandoah (he switched plans in the last couple of days and got them approved late on the 23rd) and secondly because this way he can counter a move by Lee to cross the Potomac west of the Blue Ridge.
Lee is mostly covering the lower Shenandoah Valley, and is spread out partly to allow for forage. (Though Lee himself is actually down in Richmond AIUI.)
The Union bridge engineers are at work on the bridge at Berlin.
25th October:
View attachment 517866
9th Corps moves to Berlin, where the pontoon bridge is being set up. Not all the corps moves in one go, and the bridge is still being built.
I now have Walker localized so have put his force at Paris.
McClellan asks Halleck if it's permissible to withdraw the 5th and 6th Corps from the line of the Potomac.
The letter goes into more detail than this, because it's partly about department boundaries - back in early 1862 the question of keeping Washington entirely secure was the source of an enormous amount of trouble, and McClellan wants to be absolutely certain about what troops he's allowed to take. His preferred defensive scheme would be to occupy Front Royal, Strasburg etc, and that would have been the goal of the Shenandoah movement.
26th October:
1st Corps also breaks camp, concentrating on Berlin. 9th Corps pushes over the now-bridged river to control the debouche.
This is one of McClellan's command patterns, and is something he does pretty much every time he comes up to a river where it's important to cross it but the river is not closely defended - he pushes a force (often a corps) across the river to secure control of the area as soon as he feasibly can.
The cavalry pushes south of Lovettsville.
Halleck basically punts on the question McClellan asked, and so McClellan decides that he'll be able to use 5th and 6th Corps once the Confederate army has abandoned Martinsburg. He'll just leave a small force under Morell (one of McClellan's more trusted division commanders it seems, as he was the possible replacement for Burnside during Antietam) and leave the 12th Corps at Harpers Ferry.
27th October:
9th Corps finishes crossing. 1st Corps has supply deficiencies to rectify, and does so while on the rail line; there is also some of the crossing of wagon trains here.
Meanwhile Stoneman's division is moved over the Potomac to Leesburg.
Burnside asks during this period whether it's really necessary to move the whole 9th Corps over the river during the storm, and McClellan confirms that yes, they should.
28th October:
Longstreet starts moving. (Some of the positions for Longstreet's movement are approximate.)
The news of Longstreet breaking camp causes McClellan to freeze his movement in case Longstreet is striking north (in which case he will need everything he has available north of the Potomac) and he sends a brigade-strength cavalry recce to investigate.
Lee's orders are for Jackson to move his camp from Winchester to somewhere between Charlestown and Berryville or on the waters of the Long Marsh Run owing to the deficiency of forage; Jackson is directed to:
1) Discover the movements and probable intentions of Union troops on the Potomac.
2) If required to fall back from Jefferson County (around Rippon) he is to fall back on Longstreet's new position.
3) Keep in mind the advantage of threatening the enemy east of the Blue Ridge, including crossing the mountains to threaten McClellan's flank if he's advancing east of the Blue Ridge.
Longstreet is directed to march to Culpeper ASAP but without panic.
Two brigades of Hood are sick with smallpox, and they're given a separate march route and told to basically be slower; the rest of the force is to take the best route via Chester Gap to Culpeper.
Walker's division is to remain in position until it's necessary to withdraw it, and Longstreet should inform Jackson when this takes place.
The exception is Pickett, which Lee requires Longstreet to move as fast as possible. It's also mentioned that Pickett might be diverted to Orange Court House if necessary.
Stuart's told to put a brigade into the Loudoun Valley,another brigade to the area of White Plains (to threaten the Union flank if the Union is moving towards Rappahannock, presumably Rappahannock station) and the final brigade is to stay in the Valley.
29th October:
With confirmation that Longstreet is not moving north, this is when the forces along the upper Potomac start peeling away. 9th Corps moves out to cover the whole of the upper Loudoun Valley (and possibly also to cover the terminus of the bridge at the mouth of the Shenandoah river).
This is the last point at which Pickett's position is estimated; after this point I'm pretty sure.
Slocum is formally placed in charge of the Harpers Ferry defences.
30th October:
1st and 2nd Corps cross much of their fighting echelon. Meanwhile Longstreet is moving south rapidly.
The period from the 30th October (2nd Corps stays in line with 9th Corps) to the 1st November (2nd and 9th Corps remain largely stationary on this date, making three days when those two corps are not moving) could be said to be a major delay, but looking at the map for this date we can see that a precipitate advance by 2nd and 9th Corps would have reached major difficulties about 15-20 miles further south. This is where DH Hill and Walker/Ransom are (total strength AP 14,311 based on November 10 report) and AP Hill is behind Snicker's Gap (AP Hill strength 12,239 AP on November 10 report). This combination of strength is weaker than the full 9th + 2nd Corps, but not that much weaker, and given positions at the time it would be quite feasible for other Confederate divisions to concentrate for a battle.
31st October:
At this point the only defensive forces along the upper Potomac are Morell's small force. 12th Corps is at Harpers Ferry and will be left there.
2nd Corps finishes crossing.
Walker begins moving south. All of what will formally be Longstreet's Corps next month are now on the move to Culpeper; Hood has split in half with the half going into quarantine taking a route that goes "west of" the map here.
On this date, McClellan reports enemy positions to Lincoln. Jackson's and Longstreet's forces "between Charlestown and Berryville" on the 30th. (about right in terms of latitude, though they're further west than that.) DH Hill's division near Berryville (actually AP Hill's).
1st November:
5th Corps crosses much of their fighting echelon, and 6th Corps reaches the pontoon bridge. There are now four Union corps over the river and moving south.
The "traffic jam" at Jefferson is an approximation of position, and Pickett could have preceded Walker or they could have taken parallel routes. The position is only roughly correct.
2nd November:
2nd and 5th Corps acting as a single wing under Porter seize Snickers' Gap (it's held by cavalry and AP Hill is on the other side of it). 9th and 1st move past while the gap is masked.
6th Corps follows 9th and 1st.
Pleasonon's cavalry fights a skirmish at Union and drives the Confederate cavalry several miles south of there.
There are now Confederate troops at Culpeper itself. Notably, DH Hill is still in a position to block the approach to Culpeper, which would let him at least delay a single-corps dash south.
At this point DH Hill is worried that Union troops may enter the Valley and cut off his retreat; Jackson is also concerned, enough that he tells DH Hill to warn him immediately if the Union tries crossing into the Valley and DH Hill can't retreat (as Jackson will bring up his whole corps ready for a battle)
3rd November:
5th Corps demonstrates against AP Hill, then returns to the gap. 9th and 2nd collect ready to go after Ashby's Gap, and push DH Hill away from his position at Upperville; the operations here are as much capturing the gap as if there'd been a major battle.
One division of 1st Corps is pushed forwards to take a crossing of Goose Creek.
Meanwhile 11th Corps (not shown) has taken possesssion of Thoroughfare Gap.
4th November:
2nd Corps takes Ashby's Gap, and DH Hill pulls back into the Shenandoah before marching for Front Royal. 5th Corps is still holding Snickers' Gap.
Walker moves south away from Culpeper itself, which may indicate that Lee's plan is to keep moving south.
There's a skirmish around Markham (in the approaches to Manassas Gap), where the Union cavalry gets the better of the Confederates.
5th November:
9th Corps marches to take control of Manassas Gap. There are now Union corps controlling all the main gaps in the Blue Ridge Mountains, and meanwhile 1st Corps is preparing to take Warrenton.
Lee returns from Richmond (to Culpeper).
This is also the day when Lincoln decides to sack McClellan. One of the reasons he later gives is that McClellan took too long to cross the Potomac and has been dawdling since then.
6th November:
With the bulk of the army past and 1st Corps taking Warrenton, the Blue Ridge mountain gaps are now no longer necessary. 2nd, 5th and 9th Corps all pull away from the mountain gaps, and some of 9th Corps reaches the north fork of the Rappahanock to sieze control of a bridge there.
The Union cavalry report at this point is that Jackson's corps is "in Chester Gap and beyond".
Lee's letter to Jackson around this time tells him to march south, but is a little ambiguous; when Lee writes to the Confederate SecWar the next day however he is clearer that he meant for Jackson to move.
At this time Lee's communications with Stuart indicate he's asking:
- is McClellan's right wing detached enough to risk attacking?
- is McClellan going for Chester Gap or Thornton's Gap?
Also at this time Lee is ordered to pull a brigade from his army to send it to Weldon NC.
Lee's letter to Jackson also has him warning that McClellan's intent seems to be either "trap Jackson in the Valley" or "prevent Jackson from combining with Longstreet". Lee mentions that Jackson will have to be ready to move up the Valley (south) past Front Royal.
He also tells Jackson "I request that you will have your divisions as much united as possible, so that you may fall on any one of the enemy's columns which may expose itself should the opportunity occur to crush it, and that you will endeavour to lead the enemy forward for the purpose."
To GW Smith, Lee says that the indications are that McClellan's whole army is moving towards the Rappahannock "with more activity than usual".
To Jefferson Davis, Lee says specifically that the Union has not yet taken possession of Warrenton and that there's still Confederate cavalry there; if the Union keeps moving, he will order Jackson southwest up the Valley and Longstreet through Madison towards Swift Run Gap.
On this date, Stuart appears to have suggested that Longstreet's corps should attack Warrenton, which we can mostly infer from Lee's reply the next day.
This is also the date McClellan orders the bridge at Berlin dismantled and the pontoons taken to Washington. This order went via Washington, and instead of being telegraphed the War Dept. sent the order upriver by barge - meaning it didn't reach the engineers until the 12th November. (The bridge pontoons were then delayed by another three days en route from Washington to Fredericksburg by a heavy storm.)
This action results in 5-6 days of delay in the movement of the pontoon bridge to Washington and another 3 days in their arrival at Fredericksburg. It's quite possible (though impossible to prove) that the main reason this delay wasn't spotted was the chaos attendant with swapping McClellan out with Burnside - Burnside checked on the pontoons on the 14th.
7th November:
The Union army is concentrating on Warrenton, and 9th Corps does the same thing it did earlier in the movement - secure the area on the far side of a bridge.
At this point McClellan is relieved in command (the messenger arrives), but his already-issued march orders are followed for the duration of the 8th and 9th.
(This is also around when the other half of Hood reaches Gordonsville.)
The general intel picture at this point is that Longstreet is at Culpeper and Jackson with "one, perhaps both" of the Hills near Chester's Gap and Thornton's Gap. (In fact one Hill is at Chester's Gap and the rest of Jackson is further north.)
Lee's interpretation of McClellan's movements, to Stuart, is that he's either operating by his right flank entirely or moving his whole army along the Blue Ridge (neither is currently strictly true, McClellan has broken away from the Blue Ridge). He also says that if McClellan does push Lee back he'd have Longstreet fall back through Madison to make a junction with Jackson coming out of Swift Run Gap (repeating a theme he made to Jefferson Davis).
To GW Randolph, Lee reports that McClellan is advancing and will probably reach the Hazel tomorrow. His only information on Union infantry (aside presumably from Warrenton) is two brigades of infantry at Orleans on the 6th. Interestingly this is an understatement - two
divisions reached Orleans on the 6th and the other two divisions reached Waterloo.
He also says that moving at the same speed the Union may reach the Hazel river the next day, though this may be cavalry or infantry (it's not clear).
Jackson may at this point have ordered a concentration on Winchester to strike north (we mostly know that he cancelled the concentration overnight 9th-10th November)
8th November
6th Corps holds the Thoroughfare Gap area to shield Gainesville while 5th Corps goes through.
Interestingly Stuart's command is showing signs of severe strain - Pleasonton captures his third gun from the Confederate horse artillery today, and there's not a lot of them to spare.
Lee is more explicit that Jackson must move now (he won't).
Walker has shifted to Madison Court House, possibly to defend the route by which Lee thinks he may have to retire.
9th November:
Much of the Army of the Potomac is now concentrated at Warrenton. 6th Corps leaves Thoroughfare Gap to 11th Corps (currently around Gainesville) and is under orders to move to Warrenton as well, but the change of command stops the army moving.
3rd Corps is also around Warrenton at this point - components of the corps have been seconded to 9th Corps or arriving by rail, but by now the whole corps is present (albeit spread out).
Interestingly, on this date (9th November), Lee told Stuart that there were dispatches to the effect that McClellan was concentrated "in the vicinity of Piedmont" (a theme he repeated to Jackson on 9th November and the Confederate SecWar on 10th November). This is a bit off... Lee thinks McClellan's object may be to attack Strasburg.
Later on the 10th Stuart discovered a division-plus of 9th Corps at Amissville.
This movement by McClellan is perhaps not flawless, as it could have been possible to move 6th Corps away from the upper Potomac a day or two earlier, but it is still effective. McClellan's army is moving as a coordinated force of corps acting according to the direction of a single plan of action, with no one corps courting a battle without support nearby or some other advantage at play, and the cavalry screening work is highly effective.
Whether McClellan could have reached Culpeper before Lee is a tricky topic. I am of the opinion that the task is difficult enough that McClellan couldn't really have done it successfully given the actual operational requirements at play (Lee pretty much sprinted Pickett's division down from Martinsburg to Culpeper at maximum speed and Walker's division was literally on the route McClellan would have to take to get to Culpeper). Lee could also have moved Jackson, who was closer, if he really valued getting to Culpeper ASAP.
As for Lee's performance, he's alert to the possibility of attacking McClellan if McClellan makes an error, but he seems to have missed how fast McClellan was moving down the Loudoun Valley. As a consequence of this Lee ended up in a pretty terrible strategic situation - he got Longstreet in the way where he could block McClellan's route-march to Richmond, but he also ended up with a situation in which Jackson was basically unable to contribute and where he needed Jackson to unite with Longstreet ASAP by going via Swift Run Gap, a long diversion which would have taken Jackson out of play for several days. (The extent to which this is because Jackson was immobilized by his supply problems or exercised independent command is of course relevant to the question of Lee's performance.)
Bringing the