[TexasM1A]

Gettysburg and the loss of Jackson were huge turning points.

[major_gaff]

Agreed...If Lee had Jackson at Gettysburg, the battle would have most
likely ended the first day...Ewell didn't take Culp's hill and allowed the
Federals to fortify it...Jackson would have pushed the Northern troops
off making the entire Union position untenable.

[BradyLS]

You can add the fall of Vicksburg to those two. A trifecta of crippling losses inside a month that sealed the fate of the Confederacy.