[DoodleDawg]

Lee’s critical mistake was going north to Gettysburg instead of standing on the defensive in Virginia and sending Longstreet West to help Johnson stop Grant. By July 4th 1863 the war was lost for the Confederacy.

Lee went north in 1863 in no small part to prevent his army from being split and part sent west in a futile effort to save Vicksburg.

[Tallguy]

I agree with you. Splitting up the ANV in the hopes of creating a pickup Army to what? Go at the Army of the Cumberland. George Thomas was running a corps in that Army and would eventually command it. He was a tough nut. As Chickamauga, Missionary Ridge, Nashville & Franklin would later prove.

It might have worked, but at the time it would have looked like a long-shot.