What was the turning point of the Civil War?

I have always heard that Gettysburg was the turning point. However, after studying some, it seems to me that Antietam was more of a turning point. Lee was headed north when Antietam happened. His battle plans fell into the hands of McClellan. He was still able to fight to a draw. Without the mishap of the battle plans, he most likely would have won the battle and continued north. He was unable to do so. Also, this battle gave Lincoln room to issue the Emancipation Procalamation. This seems to me to be the true turning point of the war.

The real turning point were the shots on Fort Sumter. It was all downhill from there, as in contrast to a regular war, the South could not cede (and recover) territory as it defended slaves not land. Unlike land, the slaves made contraband didn't stay behind. This was the main reason why the South could not rely on a strategy that worked in Russia, Vietnam or Afghanistan (or Washington in the American Revolution). Time was not on the South's side.

The next turning point was the boneheaded refusal of King Cotton to sell their crops to Britain in the first year of the war (when the blockade existed only on paper). This crushed the South's financial stability.

As far as the military is concerned, you make some good points about Antietam. Personally, I think the war was won in the Western theater and pick Shiloh as the turning point. If the South had managed to win that battle (a possibility), the outcome would have ruined Grant's (and Sherman's) career. With Lee winning the Seven Days, a compromise might have become inevitable.

Regarding Antietam, Lee must have been the luckiest man on earth: Having McClellan as an opponent and being stopped at the Maryland border. Lee's army which had fought from the Seven Days to Second Manassas was tattered and spent - Marylanders were shocked to see those shoe-less scarecrows. McClellan could and should have let Lee march further north and then cut his supply lines, all the while refusing battle (but Little Mac was no "Rock of Chickamauga" Thomas).

What I didn't appreciate before I visited the battlefield of Antietam is the hilly and slopy terrain. Moving just a few meters opens and closes lines of sight. Little Mac's HQ might as well have been on Mars ...

Many say that Confederate losses the battle of Chickamauga were such that the rebels no longer had the manpower to defeat or restrain General Sherman in his campaign to destroy Atlanta and march to the sea.

The Confederates had an army with which it could have tried to stop Sherman. Hood marched it to death in Nashville.

It is important to note that losses on the battlefield were responsible for only a minor attrition in manpower. Disease, desertion and local militia units are the main drains of the armed forces on both sides. In any case, the Confederate supply systems were so strained that the soldiers on the front line often went hungry and lacked ammo. Adding more men might only have choked the logistical bottleneck.

July 1863 was the turning point. Vicksburg and Gettysburg both happened then. The former cut the Confederacy in two and opened the Mississippi River to Union shipping. The latter stopped Confederate progress north.

The turning point of the Civil war was Robert E.
Lee's decision after the Second Bull run that no direct assault on Washington could succeed. The whole concept of the Antietam campaign was to scare the Federal government into submission, and so was Gettysburg. But there was no way that Lincoln would quit, and Washington DC would have to be besieged and taken...and no way for Lee's army to do that against a competent engineer. No matter how much McClellan longed for a compromise pace he'd defend Washington competently so that moment, for Lee, was the end of the Civil war.

One key turning point came before any real fighting broke out. President Lincoln's success in keeping the Border states of Maryland, Kentucky and Missouri in the Union was extremely important. Had those three states joined the Confederacy it would have significantly affected the balance of power. They had a combined population of nearly 3 million people, and Baltimore, Louisville and St. Louis were fairly significant industrial centers--not on the scale of New York City or Philadelphia, but significant enough to have added enormously to the Confederacy's industrial capacity. In addition, the Memphis & Ohio railroad (which ran through Louisville) would have given the Confederacy a valuable east-west rail conduit.

Another key was Grant's Tennessee campaign in 1862--the capture of Forts Henry and Donelson. This disrupted the Confederate defensive position in the West and resulted in much of western and central Tennessee being permanently lost to the Confederacy. Tennessee was very important economically to the South, as both an industrial center (the Iron Belt of West Tennessee, in particular) and as a source of grain and meat.

Possibly a decisive Confederate victory at Shiloh could have had a major impact, but I'm not sure. it's really hard to see, thinking about the actual course of the battle, how the Confederate attack could have been much more successful than it actually was, given the extreme inexperience of their officers and men.

Antietam is interesting because to me, it seems like a lost opportunity--not for Lee, but for McClellan. The weakness of the Army of Northern Virginia during the Maryland campaign, combined with Lee's dispersion of his forces, and the gift of the capture of Lee's orders, give McClellan probably the best opportunity of the war for a genuinely decisive victory, but the Union general failed again and again. Perhaps his worst lapse was in failing to attack Lee on September 16, at a time when he had the bulk of his army at hand, while Lee had less than 20,000 men before Jackson came up from Harper's Ferry. McClellan then badly mismanaged the battle of September 17, failing to achieve a coordinated assault, and keeping a sizable portion of his army out of the battle entirely.