No. 20. Report of Col. P. Sidney Post, Fifty-ninth Illinois Infantry, commanding First Brigade.

HEADQUARTERS FIRST BRIGADE, FIRST DIVISION, RIGHT WING, FOURTEENTH ARMY CORPS, In Camp, south of Murfreesborough, January 9, 1863.

LIEUTENANT: I have the honor to submit the following report of the part taken by the First Brigade in the late engagements, resulting in the taking of Murfreesborough:

In compliance with the order of Brigadier-General Davis, commanding division, we left camp, at Saint James' Chapel, at daylight December 26, 1862, and marched in the direction of Nolensville, this brigade being in advance. We soon came upon the enemy's cavalry. Company B, Thirty-sixth Illinois Cavalry, under direction of Captain Pease, of Brigadier-General Davis' staff, occupied the road, and the Fifty-ninth Illinois Infantry was thrown out as skirmishers on each side of it. A lively skirmish was kept up until we reached Nolensville, when the enemy appeared in force and opened upon the brigade with artillery.

The left of our line of battle rested upon the pike, the right occupying a hill commanding the town. Captain Pinney's (Fifth Wisconsin) battery opened upon the enemy and drove them from the town.

A large force of cavalry was seen moving to the right and dismounting, with the evident intention of attacking our right and rear and dislodging us from the hill. The Twenty-second Regiment Indiana Infantry was moved to the right to repel this attack, and Colonels Carlin's and Woodruff's brigades deployed, by order of Brigadier-General Davis, upon our right, soon came up, and the enemy were driven from their position and forced to withdraw their artillery.

This brigade, on the left of the line of battle, moved forward up the pike leading to Triune, Pinney's battery being on the pike, and Twenty-second Indiana and the Seventy-fourth Illinois on its right, and the Seventy-fifth and Fifty-ninth Illinois on its left. The enemy were posted in a position of great natural strength, about 2 miles from Nolensville, on the right and left of the pike, with one section of artillery on and the remainder near the road. Pinney's battery, from a knoll to the left of the pike, opened at short range with all his guns, and this brigade, on the left of Colonel Carlin's, marched steadily forward, driving the enemy from the hill, where they were compelled to abandon one piece of artillery. This march had been made in a drenching rain, and the men, exhausted by their exertions upon the muddy road and the excitements of the day, bivouacked on the field, for the possession of which they hand fought. The following day this brigade marched in rear of Colonel Carlin's nearly to Triune, it raining constantly and being very cold.

December 29, we marched in rear of Colonel Woordruff's brigade, on the Bole Jack road, toward Murfreesborough. About 2 miles from Overall's Creek, by order of Brigadier-General Davis, I deployed the brigade on the right of the road, and moved forward nearly to the creek, where we bivouacked in the rain, without fires.

On the morning of December 30, we marched across the fields on the right of the Wilkinson pike, the Seventy-fourth and Seventy-fifth Regiments Illinois Infantry deployed on the right of Colonel Carlin's brigade,