doubledog said:
One of my history teachers at University once said "May 15, not July 2-4, was the turning point in the Civil War"
On May 15, 1863, Davis accepted Lee's polite refusal to send two or four divisions from Picketts and Hoods troops to aid in lifting the siege of Vicksburg. The rest is history, loss at Gettysburg and Vicksburg. Chickamauga is proof of what could happen when the Confederacy employed its interior lines. Of course in 1864, Lee was one year older and wiser.
The great counterfactual for the Confederacy, is that for by defeating Grant and not losing at Gettysburg, the outcome of the war would have been drastically different.
I think that proposition ignores the facts on the ground, especially time-distance factors and the condition of the railroads in the CSA.
Pemberton had retreated into Vicksburg on May 17, 1863. Even if Lee had started those two divisions moving on the 15th, they wouldn't have been able to get to the vicinity of Vicksburg (remember, Grant's troops had trashed the railroads at Jackson, MS, on the 14th) in time to prevent Grant from investing the city.
Once Grant had Pemberton penned up in Vicksburg, he had more than enough troops to both keep Pemberton inside the city, and face the rest of his army around to deal with Joe Johnston coming in behind him.
I will grant that, with Hood and Pickett headed to the West, Lee probably wouldn't have lost Gettysburg - because the battle never would have been fought. Short two divisions, I doubt Lee would have launched his Pennsylvania campaign at all. Which would leave the Army of the Potomac stuck with the same problem it had had since the war started - stuck with the Army of NoVa between them and Richmond.
And with the Union capture of Knoxville in September, 1863, the CSA lost whatever value of interior lines they may have had between the Eastern and Western theaters, because any troops moving from one theater to the other had to be routed through Atlanta. Compare the movement of Longstreet's corps prior to Chickamauga to the movement of Hooker's corps to Chattanooga - the Union was able to move more troops, over a longer distance, in less time, because of the combination of efficient, well maintained railroads and river transportation.
Just speculation, but I would guess that in May-June 1863, the Union Army could probably have gotten troops from Virginia to Vicksburg almost as fast as the Confederacy if they had needed to, using railroads and the Ohio and Mississippi rivers.
