Missouri In The Civil War

From The Blue and The Gray (Volume One) The Nomination of Lincoln To The Eve of Gettysburg, by Henry Steele Commager:

The war in the Trans-Mississippi West has been unjustly neglected by historians. ....yet the fighting in the West profoundly influenced the course of these Eastern campaigns (Gettysburg, the Wilderness, etc.), and some of these campaigns, in turn, were directed to the severance of the Confederacy along the Mississippi River.

It was Missouri that was crucial. Had that state gone with the Confederacy.....