1861
June 17 Organized at New York City and mustered in for two years’ service
June 29 Left State for Washington, D.C. and duty as Infantry in the Defenses
July 30 to August 4 Attached to McCune’s Brigade and Franklin’s Brigade, Division of the Potomac
September 26 Attached to Newton’s Brigade
October 25 Designation of Regiment changed to 15th New York Engineers