Organized at Fort Union and Santa Fe, N.M., July 1 to August 13, 1861. Duty at Fort Union until February, 1862. Action at Valverde, N.M., February 21. Pursuit of Confederate forces April 13-22. Duty in Central Northern and Santa Fe Districts until May, 1862. Consolidated with 2nd Infantry, to form 1st New Mexico Cavalry May 31, 1862.