Organized at New York City and mustered in by Companies as follows: Companies "A," "B," "C," "D" and "E" October 11, 1861. Company "G" December 2, 1861. Company "K" December 3, 1861. Company "I" December 13, 1861. Company "F" January, 1862. Company "H" February 19, 1862. Companies "L" and "M" in the field April, 1864. Companies "A" to "E" left State for Annapolis, Md., October 2, 1861. Companies "G," "I" and "K" left State for Port Royal, S. C., December 14, 1861. Companies "F" and "H" left State for Port Royal, S. C., February, 1862. Served unattached, Sherman's South Carolina Expeditionary Corps, to April, 1862. District of Hilton Head, Dept. of the South, to September, 1862. District of Hilton Head, S. C., 10th Army Corps, Dept. of the South, to April, 1864. Engineer Brigade, 10th Army Corps, Army of the James, to May, 1864. Engineer Brigade, Headquarters Army of the James, Dept. of Virginia and North Carolina, to June, 1864. (4 Cos., "A," "C," "G" and "I," remained in the Dept. of the South April, 1864, to June, 1865.)