The One Hundred and Twenty-ninth Infantry was organized at Pontiac in August, 1862, by Colonel George P. Smith, and was mustered into the United States service September 8. Five companies were from Livingston county, four from Scott county and one from Rock Island county.

On the 22d of September the Regiment left Pontiac with 927 officers and men, and reported at Louisville, Ky.

On October 3, marched in pursuit of Bragg, via Frankfort and Danville, to Crab Orchard. On 17th, the Brigade was transferred to Tenth Division, Brigadier General R. S. Granger commanding. Commenced the return march October 20, and moved, via Danville, Perryville and Mumfordsville, to Bowling Green. On 21st November, the One Hundred and Twenty-ninth was sent as garrison to Mitchellville, Ky.

From the middle of December, 1863, till the first of June, 1864, the One Hundred and Twenty-ninth guarded the railroad from Bowling Green, Ky., to Gallatin, Tenn., during which time it had frequent collisions with the rebels in repelling their attacks on the railroad.

From the 1st of June till the 22d of August, it garrisoned Fort Thomas at Gallatin, which was threatened by Morgan and his entire command who approached to within about eight miles of the works, and then thinking discretion the better part of valor the celebrated General beat a retreat.

On the 22d of August, it took up the line of march for Nashville, and remained there in garrison till the 24th of February, 1864; then took the line of march for Wauhatchie Valley, arriving about the middle of March. Previous to this it was assigned to the First Brigade of the third Division of the Twentieth Corps.

On May 3d, it left with Sherman's grand army for Atlanta. On the march it participated in the battles of Resaca, Buzzard's Roost, Lost Mountain, Dallas, Peach Tree Creek and Atlanta. From the latter place it started upon the grand march to the sea, and bore its share in that and in the subsequent campaign in the Carolinas. It took a conspicious part at Averysboro and Bentonville. At the conclusion of this campaign the Regiment marched to Washington and participated in the national review there. From thence it proceeded to Chicago where it arrived the 10th of June, 1865, when it received final payment and discharge.