The south was never going to win. As Shelby Foote said the North fought with one arm behind their back, if it got bad they just had to remove the other arm.
If it got bad? You seem educated, was Antietam, Gettysburg, not bad enough for them to unloose the other arm?
I like Shelby, but I strongly disagree here. The Union was in serious peril at times; the extreme casualties led to public support for the war dwindling and many northerners wanting a truce (recognition of the CSA). They finally found a competent commander in Grant, and Sherman's ruthlessness, which finally won the war. The North sufferred from poor leadership throughout the war.
They won Gettysburg, it ended the war for all practical purposes ---