The War in the West 
Mick Werve Santa Anna Rain Photography
As I see it, the Civil War was fought on four fronts:
Eastern Theater - Anything east of the Appalachian Mountains. 
Western Theater - Everything West of the Appalachians to the Mississippi River.
This page links to everything West. I believe this was the theater where the fate of the South was sealed. During the war most of the coverage was given to events on in the Eastern Theater. Large battles such as Shiloh and Chickamauga certainly made a splash in the eastern papers and the fall of Vicksburg was celebrated throughout the North, but these were far off events and lacked the immediacy of Bull Run or Gettysburg. While most eyes watched the antics of Lee and the Army of Virginia the Union Army in the west was depriving the South of the use of the Mississippi River and other major waterways; they captured Corinth and severely restricted Southern railroad transportation. By keeping the Border States in the Union and destroying crops in disputed areas the western Union Army deprived Lee of the supplies and recruits he need to maintain his army in the face of the larger Army of the Potomac.
There is an old saw, with respect to war: armatures speak of tactics, professionals talk of supply. Shiloh and Corinth were fought to control railroads. Fort Pillow was built to prevent the Union from using the Mississippi. Fortress Rosecrans was a tremendous supply center built by Old Rosy to support his operations against Bragg, while Chattanooga was fought to control both river and train traffic. Virgina could not could not fight the war by itself.