Organized by consolidation of McClellan Chasseurs and McClellan Rifles at New York City November and December, 1861. Left State for Key West, Fla., January 5, 1862. Attached to Brannan's Florida Expedition to March, 1862. District of Key West, Dept. of the South, to August, 1862. District of Key West, Fla., Dept. of the Gulf, to November, 1862. District of Beaufort, S. C., 10th Army Corps, Dept. of the South, to March, 1863. District of Key West, Fla., Dept. of the Gulf, to April, 1863. 1st Brigade, 4th Division, 19th Army Corps, Dept. of the Gulf, to February, 1864. 2nd Brigade, 2nd Division, 19th Army Corps, Dept. of the Gulf, to July, 1864. 1st Brigade, 1st Division, 19th Army Corps, Army of the Shenandoah, Middle Military Division, to February, 1865. 1st Brigade, 1st Division (Provisional), Army of the Shenandoah, to April, 1865. 1st Brigade, Dwight's Division, Dept. of Washington, D. C., to June, 1865. 1st Brigade, Dwight's Division, District of Savannah, Ga., Dept. of the South, to July, 1865. District of Georgia, Dept. of the South, to February, 1866.Duty at Key West, Fla., till November, 1862; then in District of Beaufort, S. C. Ordered to New Orleans, La., April, 1863. Expedition from Barrie's Landing toward Berwick City May 21-26. Action at Franklin May 25. Moved to Algiers, thence to Port Hudson May 26-June 3. Siege of Port Hudson June 3-July 9. Assault on Port Hudson June 14. Surrender of Port Hudson July 9. Kock's Plantation, Donaldsonville, Bayou LaFourche, July 12-13. Duty in the Defences of New Orleans, La., till April, 1864. Moved to Alexandria, La. Red River Campaign April 30-May 22. Construction of dam at Alexandria April 30-May 10. Retreat to Morganza May 13-20. Mansura May 16. At Morganza till July. Moved to New Orleans, thence to Fortress Monroe, Va., and Washington, D. C., July 3-28. Sheridan's Shenandoah Valley Campaign August 7-November 28. Battle of Winchester September 19. Fisher's Hill September 22. Battle of Cedar Creek October 19. At Winchester, Stephenson's Depot and Kernstown till April, 1865. Moved to Washington, D. C., April 21-22, and duty there till June 1. Grand Review May 23-24. Moved to Savannah, Ga., June 2-6. Duty there and at Hawkinsville, Ga., till February, 1866. Mustered out February 9, 1866.