No matter the service branch, within both the Republic Military and its Imperial successors holders of the rank of First Sergeant were responsible for the enlisted and non-commissioned officers who served within company-sized units. As the lead unit NCO, they served as a point of contact on the chain of command, bringing matters to the attention of the company's commanding officer. Within the Marine Corps, first sergeants also served as senior instructors for advanced training courses for both enlistees and officers.