The following is taken from New York in the War of the Rebellion, 3rd ed. Frederick Phisterer. Albany: J. B. Lyon Company, 1912.

This regiment was accepted by the State May 9, 1861, and designated the 15th Regiment of Infantry. It was organized in New York city, and there mustered in the service of the United States for two years June 17, 1861. The regiment was intended and recruited for an engineer regiment, and was converted to that arm of the service by the War Department October 25, 1861. In January, 1862, Company I was reorganized of three years' recruits. June 18, 1863, the three years' men in the regiment were transferred to Companies A, B and C, and June 25, 1863, the two years' men of these three companies and all the other companies, their term of service having expired, were, commanded by Col. Clinton G. Colgate, honorably discharged and mustered out at New York city. To the battalion left in the field, there was assigned as Company D the company enlisted for the 2d Volunteer Engineers, on the 9th of October, 1863, and in March, 1864, another company recruited for the regiment joined it as Company E. In November, 1864, the reorganization of the regiment was completed by the addition of seven companies as F, G, H, I, K, L and M; Companies H, I and K were formed of recruits originally enlisted for the 50th Engineers; Company M was originally organized for the 175th Infantry, and Company L had originally been organized as a company of the 189th Infantry. The new companies were mustered in the United States service, D and E for three years; F and L for one and three years, and G, H, I, K and M for one year.

The companies were recruited principally — first organization - A, E and F, also G -New York Light Infantry — in New York city; B and C in Brooklyn; D in New York city, Brooklyn and New Jersey; H in New York city, Brooklyn, Flushing and Williams-burgh; I and K in New York city and Brooklyn; second Company I in New York city; of the second organization, D in New York city; E at Kingston; F at Albany, Kingston, Caneadea, Tarrytown and Salina; G at Malone, Clymer, Harmony, Hector, Union, Newark Valley, Dansville, Lindley, Portville, French Creek, Owego, Lodi and Seneca; H at Malone, Syracuse, Owego, Elmira, Auburn and Dunkirk; I at Elmira, Owego, Avon, Oswego, Utica and Seneca; K at Lima, Goshen, Avon, Cicero and Syracuse; L at Utica, Avon, Auburn, Syracuse, Lyons, Goshen and Elmira; and M at Syracuse, Auburn, Rochester, Owego and Elmira.

The regiment, commanded by Col. J. McLeod Murphy, left the State June 29, 1861; it served as infantry at and near Washington, D. C, from June 30, 1861; in McCunn's Brigade from July 20, 1861; in Franklin's Brigade, Division of Potomac, from August 4,1861; in Newton's Brigade from September 26, 1861; at Alexandria, Va., receiving instruction as engineers from November, 1861, and in the Volunteer Engineer Brigade, Army of the Potomac, from March, 1862; three companies — A, B and D—'With General Terry's force in North Carolina from January, 1865, and with the Army of the Ohio from March, 1865. Commanded by Col. Wesley Brainerd, it was honorably discharged and mustered out at Washington, D. C., Companies E, F, G, H, I, K and L June 13, Company C June 14, and Companies A, B and D July 2, 1865.

During its service the regiment lost, killed in action, 4 enlisted men; of wounds received in action, 1 enlisted man; of disease and other causes, 3 officers, 121 enlisted men; total 3 officers, 126 enlisted men; aggregate, 129; of whom I enlisted man died in the hands of the enemy.