"Even if Lee had been victorious, he could not have ended the war that day or secured "inevitable" Confederate victory" The South was hoping for a negotiated peace settlement which would recognize the South as a nation.
To achieve this, they first had to convince the North it would never defeat them militarily.
And, Lee also wanted to put a scare into the northern population -- that they were not entirely safe from this war.
And up until Gettysburg, Lee had assembled a string of lopsided battlefield victories -- even when outnumbered -- which could easily be spun into a great myth of vast Southern superiority.
And, remember, the North had an illustrious general, just waiting in the wings, eager to run for President and negotiate with the South...?
Wasn't his name Westly Clark? No, no, McClellan ;-)
The South was hoping for a negotiated peace settlement which would recognize the South as a nation.Indeed - but that would never have happened unless the UK or France or both had intervened to force such a conclusion.
While France was very willing to get involved, they did not want to get involved unless the UK did.
And the UK, despite Confederate hopes, had no desire to get involved at all - they would never have intervened militarily on behalf of a slave power, no ministry would have survived such a decision.
No, no, McClellan ;-)
The Union, whether headed by Lincoln or McClellan, would never have accepted a separation. McClellan would have agreed to a reunion on terms ridiculously and scandalously favorable to the South, but not a separation. McClellan was not as bad as Wesley!
Remember also that there was a growing faction of Southerners in East Tennessee, the Western Carolinas and Northern Alabama and Mississippi who were not particularly jazzed about the Confederacy anymore, either.
Given the right inducements a good number of Confederates would have preferred a reunion on their terms to living on a border that might erupt in war again soon.
After all, even if the Confederacy had succeeded in separating from the Union and concluded a treaty to that effect, the entire point of the Confederacy in the first place was to expand the slave economy into the western territories that the federal government refused to open to slaves.
And, remember, the North had an illustrious general, just waiting in the wings, eager to run for President and negotiate with the South...? Had McClellan won in November 1864 he still would not have been inaugurated until March 1865. Look at the condition of the confederacy at that point and it's hard to believe that McClellan, or anyone else, would have caved in and surrendered to them.