In Ken Burn's excellent documentary The Civil War, noted Civil War historian Shelby Foote (a Southerner), says he feels the South never really had a chance and that the North was "fighting the war with one hand behind its back." As evidence, he cites Harvard and Yale having their annual boat races throughout the duration of the war, and a few other things that show the sheer manpower and resources the North had at its disposal. From what I know and what I have read....I agree with him 100%. The South had some great generals and as much fighting spirit as anyone could hope an army to have, but in the end the North simply had more money, more resources, and more men than the South could ever hope to compete with.
Of course, those guys have forgotten more than I'll ever know - but I think they did have a chance. I think, in the end, their motivations were not enough to justify the type of guerilla tactics that they probably would have been reduced to. The sheer magnitude of the garrisons and supply lines the North would have had to maintain would have made long term occupation very difficult. I think the best chances were obviously pre-Antietam (through some sort of European intervention) and in 1864. If Johnston was was given the chance to hold on to Atlanta, McClellan may have had an outside shot of winning the election. Not really sure what might have happened after that.
