Organized at Portland, Maine, and mustered in October 4, 1861. Left State for Baltimore, Md, October 6. Attached to Dix's Division to November, 1861. Railroad Brigade, Army of the Potomac, to April, 1862. 1st Brigade, Williams' Division, Dept. of the Shenandoah, to June, 1862. 1st Brigade, 1st Division, II Corps, Army of Virginia, to September, 1862. 1st Brigade, 1st Division, XII Corps, Army of the Potomac, to April, 1863. Headquarters XII Corps, Armies of the Potomac and Cumberland, to February, 1864.