But in what direction to advance was an unsettled problem. Rosecrans was strongly urged from Washington to move at once into East Tennessee, threatening Chattanooga and giving encouragement to the Unionists in that quarter. But Nashville was in serious danger. It had been held by a comparatively meager garrison during the Perryville campaign, against a strong Confederate force under Breckinridge, and there was more than a chance that Breckinridge might now capture the position unless Negley, with the two divisions under his command there, could be promptly supported. The importance of Nashville to the Federal armies as a secondary base of supplies was very great. Whether Rosecrans should campaign to the east, west or south, his need of depots at Nashville must be imperative.

While he was pondering the question of an objective, Bragg settled it for him. The Confederate general had retired from Kentucky rather of his own choice than under compulsion. He had suffered no disaster. At Perryville indeed he had had the best of the fighting for a large part of the day, and he had retired in the night rather with the purpose of giving battle again at some more favorable point than with intent to avoid battle with an enemy in strongly superior force. That enemy had not seen fit to follow and press him, and so there had been no further trial of conclusions. The Confederates had indeed failed to capture Louisville and establish themselves on the Ohio, but they had met with so much success not only in the various actions fought but also in demonstrating their ability to advance or retreat at will, that they came out of the campaign feeling themselves, in effect, victors. They were full of spirit and eagerly ready for further campaigning.

With his army in this mood and with a secure base behind him at Chattanooga, Bragg promptly moved upon Murfreesboro, with manifest intent to join Breckinridge and carry Nashville with a rush, if Rosecrans should fail to succor that strategic key to the situation.

Murfreesboro lies on the Nashville and Chattanooga railroad, a scant forty miles southeast of Nashville. The country between is open and so completely unobstructed by physical features of difficulty, that the railroad shows scarcely a curve in its course between the two points.

In view of Bragg's advance there was but one course open to Rosecrans. He must strengthen the defenses of Nashville and concentrate there for defensive and offensive operations.

He promptly threw a strong force into Nashville and soon his entire army was concentrated there, except such detachments—and these were large—as were employed in rebuilding the railroad between Louisville and Nashville, which the Confederates had destroyed, and those other and still larger detachments which were necessary to defend that vitally important line of communication against the ceaseless activity of Forrest and Morgan, who were making themselves destructively ubiquitous.

Rosecrans's activity was such that he succeeded in rendering Nashville secure before Bragg could carry out his purpose of assailing that stronghold. Still Bragg did not despair of his purpose. He sent peremptory orders to the forces around Corinth, either to send him strong reinforcements or to carry on such a campaign in their own districts as should compel Rosecrans to weaken himself at Nashville by sending heavy reinforcements to the west.

Meanwhile Bragg fortified himself at Murfreesboro, establishing his lines along and across Stone river—a little, easily fordable stream—about two miles in front of the town.

Rosecrans decided to assail him there, and to that end advanced with 47,000 men. His march began on the twenty-sixth of December, and by the thirtieth he was in position to assail his enemy with an effective force of 43,700 men. His plan of battle was to throw forward his left wing in force, envelope his enemy's right and crumple up his lines by pushing into action a ceaseless stream of fresh troops, wheeling his divisions to the right as they should be successively brought into action.

But Bragg was also an officer of great energy and activity, and he had under his command a force nearly if not quite equal to that of his foe. He was at disadvantage during Rosecrans's sudden and unexpected advance from Nashville, from the fact that he had sent away his cavalry under Wheeler, Forrest, and Morgan to assail Rosecrans's communications at a time when that general was not expected to take the initiative in a winter campaign in the field. But now that Rosecrans was in his front, and obviously intending immediate battle, Bragg in his turn determined to assume the aggressive and himself bring on the action. His plan was absolutely identical with that of Rosecrans, namely to push forward his left wing, envelope and crush his enemy's right and by successive right wheels to destroy his foe or drive him into retreat. Thus Rosecrans intended to begin the battle at one end of the line while Bragg meant to begin it at the other.