Please, no one here is arguing against Lee's generalship in the field nor the quality of the ANV, where did you get that? In fact, part of my argument for the viability of a Western Invasion is based on confidence that Lee and the ANV can hold off any serious Union advance in the East in his familiar haunts in Northern Va. by fighting his usual style of the strategic defense by tactical offensive. You are the one who seems to doubt Lee's a and the ANV abilities to do so.
There was at that time, little or no evidence from the history of the war up to that time, than an invasion of the North would result in any more success, tactically or strategically, than from all other previous battles. Whereas, Bragg's invasion of Ky, at least yielded tangible strategic results, that in the end neither he nor Lee or confederate gov't could or would take full advantage. But, IMO, even just the delaying the loss of Chattanooga by a Year, was a better strategic result than was even possible by the invasion of Pa., and the fact that Lee could not or would not see the fallacy, of trying to affect the strategic advantages of the North and disadvantages of the South, by a tactical victory in the East, reflects, I say again, on the question of just how good was Lee's strategic mind.
The thing is, either Lee has a realistic prospect of a victory in the field in an
invasion against a Union army of comparable size to his own, or he cannot.
If he cannot, then the only sorts of thing the Confederacy should be doing are:
1) Defending.
2) Offensive campaigns in which any prospect of battle involves the Confederates having significantly superior force.
This is because if Lee can't win an offensive victory in the field against a Union army of comparable size to his own, then it's not reasonable to expect that Bragg can (as that would require Bragg to significantly
outperform Lee). That means the main Confederate strategy becomes "outlast the enemy".
This is a question of strategic allocation of resources in 1863.
If an offensive and the defeat of a peer Union army is possible, then it may as well be one which takes place under Lee. If it is not, then it needs to be demonstrated that whatever Bragg would be doing with the army is a safe offensive - or that whatever Bragg is doing with the army is a viable delaying tactic.
As for the matter of delay, if that is policy the goal is essentially for the Confederacy to not lose in area A
well before it loses in area B.
In the West, there is a lot of delay that is "built in" because of the long distances and logistical difficulties involved; in the East, the distances are short and an advance is logistically easy except for at most one gap that needs to be traversed which
is logistically difficult (getting over the Rapidan) but the Union can just skip it if Lincoln ever gets over his hang up about the waterborne route.
So the case that needs to be made is that one of these things is true.
- if sending Longstreet to Bragg, then the benefit from whatever Bragg does with him results in a delay that means the West
will not fall significantly sooner than the East.
- if not sending Longstreet to Bragg and retaining Longstreet in the East, but not conducting an invasion of the North, then that the lack of casualties will make the Confederacy as a whole able to hold out longer.
Both of these depend on the "there was no prospect for a major offensive victory" to be true.