My personal impression is that Antietam/Sharpsburg was the decicive turning point and that the battle (bloodiest single day in US history) is often underestimated because of the tactical stalemate and the utterly wasted chance to exploit the exhaustion of the southern army and its risky position with just a single ford across the Potomac as an escape route.
It has often been said that the north did win the war mostly because of the northern victories in the western theatre and this is quite true. But if the south ever had any chance at all to win against the numbers, the industrial superiority of the north and the blockade by the US navy it was based on the intervention of European powers (England and France) on behalf of the south which was only likely to happen in case of a spectacular victory on Northern soil
before the issue of the proclamation of emancipation.
The chance for a British intervention was probably never as high as in November 1861, not so much because of southern success on the battlefield, but because of the
Trent-Affair, but even after this the possibility of a British intervention for the South was a looming possibility. If Britain had joined the war the North would have been in a two front war between the Southern States and Canada and the Royal Navy would have had the means to end the blockade.
Indetermined as the tactical outcome of the battle of Antietam was and in spite of it being yet another wasted chance (after the similarly wasted chance of the Peninsula Campaign), the political consequences were tremendous. Lee's retreat/escape (a retreat without alternative option since he could have neither made a lasting stand against the north in his precarious position) turned the tactical draw into a strategic victory which (and this is the decisive part) allowed for Lincoln to announce the proclamation of emancipation without it appearing like the last desparate call of a defeated north.
Never after was there a realistic chance of any European country to ally with a nation fighting on behalf of the maintainance of slavery against the central government that had announced its abolition. Sure enough the declaration of emancipation didn't say anything about the slaves held in the border states which had (more or less) remained in the union (Deleware, Maryland, Kentucky and Missouri) or about those in regions no longer in a state of rebelion, that is the regions already occupied by the north (including among other the largest town in the south, New Orleans), but the message that slavery had no future was clear and the loss of face to support the faction now declared to fight on behalf of slavery would have been more than any European power could have accepted.
This, in my opinion, was the moment the South lost the chance of winning the Civil War.
Many people may argue this and traditional "lost cause" view of things (but also many who do not sympathise with the south) that the battle of Gettysburg marked the "High Water Mark" of the Confederacy.
While I do see where this view is comming from I still do not share the view that even a southern victory at said "high water mark" would have won the war for the south. If Pickett's charge had been an unexpected stunning success for the south it still wouldn't have made the capture of Washington a matter of course. There were still strong reserves in the fortifications surrounding the capital to confront Lee, whose army would have been reduced in numbers and ammunition supplies to the point that even a victory at Gettysburg might have been followed by a retreat made necessary by the need to recover from a victory that would have still bleed the south direly.
Another view of the last decicive moment of the civil war is that the south would have won in case the presidential election of 1864 would have resulted in an election of George McClellan. There is some credit to this view and I heard of what if scenarios in which J.E. Johnson was not replaced by Hood and Atlanta not taken prior to the election and a McClellan victory as a consequence. However, it is often overlooked (perhaps in part due to the election propaganda of the republicans) that McClellan never advocated a peace with the South on the basis of a southern independence. His willingness to withdraw the emancipation would most likely have resulted in turmoil and revolts of the deceived black population. Most likely the war would have been prolonged by this (with the South having reached a point where even the promise of maintaining their "peculiar institution" for the time being, would not have made them withdraw their claim of independence even in the face of a military defeat that would not have been undone even if Lincoln had not been reelected in 1864).
Perhaps the most important message of the election of 1864 was the high vote for Lincoln among the very soldiers who had two years earlier been very angry about the dismiss of McClellan who was quite popular among the soldiers of the army which he had pretty much organized and put in shape (that credit remains to the man who was quite fit to create an army which we was unfit to command on the battlefield). The high vote for Lincoln among the soldiers is a sign for the northern will to "see this through" and "finish the business" which is often neglected when compared to the fighting spirit in the south.
PS: Thanks a lot for a thread for the historians Chomper
I am very curious for other opinions since this above is my personal view which is based on facts but certainly not irrefutable and I am very much interested in an exchange of opinion not based on proving oneself right but rather on the exchange of points of view to widen the view of everyone interested in the topic
