Recruiting for the regiment commenced on April 18, 1861, at the Arsenal, at the corner of Sixteenth and Filbert streets in Philadelphia. Many members and the organization of the unit was drawn from the 1st Pennsylvania militia regiment. Both Charles P. Dare and David B. Birney retained their positions as colonel and lieutenant colonel, respectively. Capt. George C. Spear of Company A was elected major. Three days after recruitment started, the newly formed regiment left for active duty.