Mustered into the United States service in May, 1861, for three years. It was stationed at various places in Maryland during the ensuing year, doing guard duty most of the time along the Upper Potomac. In March, 1862, it crossed into Virginia with Banks's troops, and moved up the Shenandoah Valley. The regiment was stationed at Front Royal, Va., where, on May 23, 1862, it was surrounded and cut off by Jackson's rapid advance, and forced to surrender, losing 14 killed, 43 wounded, and 535 captured; Colonel Kenly was seriously wounded. Their gallant opposition retarded Jackson's advance, giving Banks ample time to withdraw in safety from the Valley. The regiment was paroled in September, and two months later it was declared exchanged. In the meantime the small part of the regiment which had escaped capture, together with some recruits, preserved the organization, and was assigned to the Maryland Brigade (First, Fourth, Sixth, Seventh, and Eighth Maryland). In March, 1863, this brigade was assigned to Kelly's Division, Eighth Corps, and served in the West Virginia campaign. Upon Lee's invasion, the brigade retired into Maryland, where, on July 10, 1863, it was assigned to the First Corps. In March, 1864, it was transferred to the Fifth Corps. The regiment reenlisted, and on its return from its veteran furlough the battalion of veterans arrived at the Harris Farm just in time to enter that action, its loss there amounting to 6 killed, 29 wounded, and 2 missing; a heavy percentage of loss as only a small number were engaged. Colonel Dushane was killed at the Weldon Road, and Colonel Wilson fell at Dabney's Mills.