That is a good point. Who knows what could have happened if somebody else led the charge. Up until Gettysburg the Union was pretty much losing the war. This was the first major victory for the North. It was such a huge battle that the outcome of the war was almost decided on the outcome of Gettysburg. Lee refused to give up because of his stubbornness, which he was known for. The war went on for two more years which cost more lives. It should have ended at Gettysburg but Lee refused to accept defeat which continued to cost him.
Gettysburg didn't doom the South, it just made them loose valuable men and prevented a victory at that time. The war was really lost in the west. Lee pretty much held his ground until the very end, not so with Bragg, Johnston, Hood, etc.
Tim,
As Joshua points out in his post, most big battles in the West were Union victories. By the time of Gettysburg, the North won the following victories in the Western and Trans-Mississippi Theaters:
Boonville, June 1861--helped hold Missouri in the Union
Forts Henry and Donelson, Feb 1862--pushed Confederacy out of Kentucky and opened up Tennessee to attack
Nashville, Feb 1862--surrendered without a fight, remaining in Union hands throughout the war
Pea Ridge, Mar 1862--ended a Confederate push in Arkansas
New Madrid, Island #10, New Orleans, Mar-Apr 1862--captured most of the Mississippi River
Shiloh, Corinth Mar-Apr 1862--drove Confederate Army further south
Memphis, June 1862--capture of another key city
Iuka, Corinth, Sep-Oct 1862--defeat of Confederate attacks intended to help Bragg in Kentucky
Perryville, Oct 1862--pushed Bragg out of Kentucky, which remained in Union hands the rest of the war
Prairie Grove, Dec 1862--stopped another Confederate push in Arkansas
Stones River, Dec 1862-Jan 1863--start of the campaign to push Bragg out of central Tennessee
Port Gibson, Jackson, Champion's Hill (May 1863)--continuous victories in Grant's Vicksburg Campaign, forcing the seige.
Milliken's Bend (June 1863)--defeat of Confederate forces sent from Louisiana to help at Vicksburg
Also, don't forget the Union victories in the Carolinas during the first part of the war; Hatteras (Aug 61), Port Royal (Nov 61), Roanoke Island & Elizabeth City (Feb 62), New Berne and Fort Macon (Beaufort) (Mar-Apr 62), and Fort Pulaski (Apr 62), which gave the Union control of the Albemarle Sound and North Carolina coast (except Wilmington).
Don't fall into the trap of looking at the whole Civil War in the context of the Army of the Potomac vs the Army of Northern Virginia.