. Rosecrans was also anxious that the rebel
cavalry should be distant when he advanced, as his army was very deficient
in cavalry.

Morgan's cavalry made a raid upon Hartsville, Tennessee, and on the 7th of
December captured a brigade of infantry placed there by Thomas to guard
the crossing of the Cumberland. The capture of this brigade was due to
neglect of the simplest precautions. No outposts or sentinels of any kind
seem to have been used, and the rebel cavalry was in line only 400 yards
away before it was discovered. The infantry turned out in great disorder
and was badly managed, so that it was forced to surrender. No word was
sent to a supporting brigade but a few miles away, and Morgan was allowed
to get away without any loss. He then started for Kentucky and on the 27th
of December captured Elizabethtown and destroyed a large section of
railway. He kept on to Muldraugh's Hills and destroyed two trestles, each
about 500 feet long and 90 feet high. The railway communication was thus
effectually broken, and if Rosecrans had remained in Nashville the
condition of his army would have been critical. But having completed his
preparations and finding the conditions favorable, owing to the absence of
Bragg's cavalry, Rosecrans advanced from Nashville on the 26th of
December.

Mitchell's division was left to garrison Nashville so that Thomas's
command was reduced to Negley's and Rousseau's divisions and Walker's
brigade of Fry's. McCook's and Crittenden's wings were on the pikes south
and southeast of Nashville. The main body of Bragg's force, consisting of
Polk's corps and part of Breckenridge's division of Hardee's corps, was at
Murfreesboro'. The remainder of Hardee's corps was near Eaglesville, about
twenty miles west of Murfreesboro', McCown's division of Hardee's corps,
with a division under Stevenson, formed a separate corps under Kirby Smith
at Readyville, twelve miles east of Murfreesboro'.

Rosecrans' plan was to advance in three columns, refusing his right.
McCook's corps was to use the Nolensville pike, Thomas the Franklin Pike,
and Crittenden the main Murfreesboro' pike. McCook was to attack Hardee
and if the enemy held his ground and was reinforced Thomas was to support
McCook. If, however, Hardee retreated, McCook was to detach a division to
pursue or observe him and move with the remainder of his corps so as to
come in on the left rear of the main rebel force. Crittenden was to attack
supported by Thoma