First Bull Run - McDowell had almost as many men who didn't go into action as did; even if JE Johnston or Beauregard had tried to advance, now the shoe is on the other foot and they would be attacking a defending force - which can take a position north of any number of water lines.
Shiloh - The problem for the rebels is AS Johnston attacked Grant's 49,000 with his own 45,000 on the first day, and even with the advantage of operational surprise, Grant's force held - with an entire division that wasn't even engaged in reserve. And the army artillery. And the gunboats. Amd then on the second day, Buell's 18,000 arrived...
Gettysburg - not really; the rebels had to attack and, not surprisingly, a veteran army under a solid commander on the defensive cleaned their clocks. Plus, Lee, forgetting Malvern Hill yet again.
Vicksburg - Grant being forced away from anything by Pemberton and JE Johnston is completely unlikely, especially since Grant turned in his best maneuver campaign ever in the summer of '63.
'64 - The US was so close to victory they could taste it; there's a reason 50 percent of Sherman's 3-year-veterans reenlisted that year for the duration.
Best,
I'm not saying any of those was probable, but that IF some combination of those had occurred, they could potentially impacted Union determination to win.
I disagree re Gettysburg, though. The whole affair was closer than you suggest. Ewell might have taken Cemetary hill on the first day, had he pushed, denying the Union the good ground. Alternately, if the rebels had taken and held the Round Tops it could have made much of the Union position vulnerable. Finally, Lee did not absolutely have to attack. As you note, he ignored lessons from throughout the war in attacking (especially on the 3rd day). He could have tried to maneuver around the Union army, putting Union cities at some risk. This option is explored well in Gingrinch's book "Gettysburg."
Re Gettysburg - put it this way, the ANV had to attack if Lee wanted to achieve anything from the operation; he could try and manever, but his army wasn't any fresher and it is certainly much more poorly supplied than Meade, and Meade was both operating on interior lines and outnumbered Lee by more than 20,000 men (25,000 according to Battles and Leaders), so the liklihood of anything decisive coming from that is vanishingly small.
Likewise, they simply could have withdrawn, presumably outdistancing Meade et al on the march south, but that would have been a waste of time and horseflesh.
The issue, again, is that by anything resembling a rational accounting, the rebellion was doomed to failure from Day 1. It had to be beaten down, of course, but the correlation of forces - economic, political, military, and demographic - was such that as long as the US was willing to fight, the end was predetermined. All the rebels ever had in abundance, as Margaret Mitchell noted, was arrogance...
One can posit the rebels having a streak of luck that would make anyone living in a ratonal universe blush (and, after all, one makes their own luck - and, as was said by Jesse Oldendorf after Surigao Strait: "never give a sucker an even break"), or McClellan or someone else becoming a Petain, but that's out there in the Twilight Zone.
There are those who wish really hard otherwise, but that's all they ever were - wishes.
Best,
One thing at Gettysburg is that the Union army, although they had lost consistently in the past, by this stage they were a hardened, discipline army looking not only for a fight, but for a victory. They would have held Cemetery Hill on the first day, as they did on Little Round Top the second regardless of who was coming at them.
All very true... and to be fair, the Army of the Potomac, as a military organization, did not lose on the Peninsula - although its commander certainly did.
In the Seven Days, for example, all but one of the battles, including the last and arguably most significant, Malvern Hill, was a US victory in the field...
Not so much at the headquarters, of course, but that was not the average Billy's fault, much less most of the officers, up to and including the corps commanders...
Best,
That may be true, but the Army of the Potomac did not really have any successful - or perhaps significant - victories until Gettysburg. Antietam may count, but Fredericksburg and Chancellorsville hurt them enough to learn from turning a defeat into a victory.
And you also have to consider that the AoNV, as well as its commander Lee, did believe in their invincibility due to their consistent victories since he practically took command of the army.
I dunno; North/South Korea and China/Taiwan still refuse to acknowledge the legitimacy of their enemy's respective governments.
True, there's no way the South is going to win them all, but a few could make a difference:
1861: First Bull Run -- a more decisive Southern victory, DC threatened
1862: Shiloh -- very nearly a Union loss. If the South crushes Grant and Buell against the river, the US loses huge forces and Grant (either to death, capture, or he's relieved).
1863: Gettysburg -- a near run thing. If Lee wins and routs Union forces, there could be panic as major northern cities are threatened.
1863: Vicksburg -- Grant forced away, limiting US river use
1864: Just more US blood in general
Well if they've signed a peace treaty that means they've been compelled to at least recognize the Confederacy. The tragedy for all Unionists is that if foreign recognition is achieved it will be hard to put Humpty Dumpty back together again and the Confederacy will be de-facto an independent nation.
Otherwise the biggest issue which will force at least some level of discourse is economics. The regions of the US were pretty interdependent, the mills of New England couldn't function without Southern cotton and the South needed the cheap industrial parts of New England for its own small industries (here though New England will see itself competing with England for that market so that's a semi-amusing ripple). The Mid West also wants Southern tobacco and crops/cattle while the South wants Midwestern grain and other staples not easily grown there.
The other fact is you can't just up and ignore a new and large neighbor on the block.