Organized, officered, and equipped by August 22, 1861, and on the following week it went to Washington, encamping on Meridian Hill. It was assigned to the Second Jersey Brigade, which was composed of the Fifth, Sixth, Seventh and Eighth New Jersey regiments. This brigade afterwards became the Third Brigade of the Second (Hooker's) Division, Third Corps. In December, 1861, it moved to Budd's Ferry, Md., about 45 miles below Washington, where it remained on duty until April, 1862, when it joined McClellan's Army, then in front of Yorktown. Hooker's Division did most of the fighting at Williamsburg, in which action the regiment lost 9 killed, 67 wounded, and 27 missing. At Chancellorsville the brigade was conspicuous for its efficiency, the Fifth capturing three of the enemy's flags; its casualties there were 13 killed, 102 wounded, and 6 missing, out of 320 present, as officially reported. General Mott, the gallant commander of the brigade, being wounded, Colonel Sewall succeeded him during the rest of the action; General Berry, the division general, was killed. At Gettysburg, the casualties were 13 killed, 65 wounded, and 16 missing; Colonel Sewall was among the wounded. In March, 1864, upon the discontinuance of the Third Corps, the brigade was transferred to Mott's Division of the Second Corps; it ceased to exist as a distinctive Jersey Brigade, as four regiments from other States were added. The losses of the regiment in May and June, 1864, were 15 killed, 129 wounded, and 12 missing. It was mustered-out at Trenton, N.J., September 7, 1864; the recruits and reënlisted men were consolidated into a battalion of four companies, and transferred to the Seventh New Jersey.