As General Grant's legions moved inexorably down a solid front from the Appalachians to the Mississippi, the distance became so great that not even his legendary command could direct the corps at the far reaches of his line. Thus it was that Grant's army split in two, mostly focusing on Mississippi in the West, while Old Rosey came back from Missouri to command the troops who had so recently driven Beauregard from Chattanooga.
Yet Rosecrans seemed to have a consistently crippling effect upon the new Army of the Cumberland; a solid 3-2-3 general himself, he nonetheless caused his several subordinates to each suffer a -1 penalty to both Strategic and Offensive skills. Now such legendary heroes as Dodge and Whipple, nay even Buell himself, were reduced to quivering kittens, motionless in the mountains while the plains of Georgia sat wide-open before them.
At first, Lincoln accepted that Rosecrans had been selected for this post because it did not require lightning offensives, and perhaps the new Army's growing pains would resolve with time and acquaintance. Yet as the months dragged by, the Curse of the Cumberland continued, with the same malaise affecting every corps in the army. Maybe Hooker will have to come West...