Well, there were two important turning points of the war.
The first one is the Battle of Gettysburg. Basically, Robert E. Lee and the Confederate Army marched into Pennsylvania to capture a town in order to cut off Washington D.C from the rest of the Union, which could force a decisive surrender of the Union. However, Union forces met with Confederate forces, resulting in a bloody battle that ended with the most notable conflict of the battle of General Pickett's Charge, which was the final conflict that resulted in the defeat of the Confederates. This was decisive because General Lee did not attempt to strategically end the war after this battle. Which further meant that Lee would have to fight an already pro longed war when the South did not have the resources or the industrial capacity or the able bodied men to serve as soldiers as the North did.
The second turning point I would say would be the appointment of General Ulysses S. Grant of the Union forces by Lincoln, due to that he was a brilliant general and already known war hero, and for the fact that of his only acceptance of enemy surrender conditions as "unconditional", hence his nickname "Unconditional Surrender Grant".
Crete is the best option :)
