governor for that State, and so threatened Louisville that Buell was compelled abruptly to abandon his eastward march and, turning to the north, run a neck-and-neck race to save Louisville from rebel occupation.  Successful in this, Buell immediately turned and, pursuing the now retreating forces of Bragg, brought them to bay at Perryville, where, on October 8, was fought a considerable battle from which Bragg immediately retreated out of Kentucky.

While on one hand Bragg had suffered defeat, he had on the other caused Buell to give up all idea of moving into East Tennessee, an object on which the President had specially and repeatedly insisted.  When Halleck specifically ordered Buell to resume and execute that plan, Buell urged such objections, and intimated such unwillingness, that on October 24, 1862, he was relieved from command, and General Rosecrans was appointed to succeed him.  Rosecrans neglected the East Tennessee orders as heedlessly as Buell had done; but, reorganizing the Army of the Cumberland and strengthening his communications, marched against Bragg, who had gone into winter quarters at Murfreesboro.  The severe engagement of that name, fought on December 31, 1862, and the three succeeding days of the new year, between forces numbering about forty-three thousand on each side, was tactically a drawn battle, but its results rendered it an important Union victory, compelling Bragg to retreat; though, for reasons which he never satisfactorily explained, Rosecrans failed for six months to follow up his evident advantages.

The transfer of Halleck from the West to Washington in the summer of 1862, left Grant in command of the district of West Tennessee.  But Buell’s eastward expedition left him so few movable troops that during the summer and most of the autumn he was able to accomplish little except to defend his department by the repulse of the enemy at Iuka in September, and at Corinth early in October, Rosecrans being in local command at both places.  It was for these successes that Rosecrans was chosen to succeed Buell.

Grant had doubtless given much of his enforced leisure to studying the great problem of opening the Mississippi, a task which was thus left in his own hands, but for which, as yet, he found neither a theoretical solution, nor possessed an army sufficiently strong to begin practical work.  Under the most favorable aspects, it was a formidable undertaking.  Union gunboats had full control of the great river from Cairo as far south as Vicksburg; and Farragut’s fleet commanded it from New Orleans as far north as Port Hudson.  But the intervening link of two hundred miles between these places was in as complete possession of the Confederates, giving the rebellion uninterrupted access to the immense resources in men and supplies of the trans-Mississippi country, and effectually barring the free navigation of the river.  Both the cities named were strongly fortified, but Vicksburg, on the east bank, by its natural situation on a bluff two hundred feet high, rising almost out of the stream, was unassailable from the river front.  Farragut had, indeed, in midsummer passed up and down before it with little damage from its fire; but, in return, his own guns could no more do harm to its batteries than they could have bombarded a fortress in the clouds.