Colonel Ragnar H. Peterson was commissioned an Infantry Officer upon graduation from Officer Candidate School Class 167-A, 6 February 1943. His first duty assignment was as Unit Officer 3rd Infantry Training Battalion, Camp Wheeler, Georgia. | His subsequent duty assignments include: Platoon Leader, Company H, 442nd Infantry Regiment, Camp Shelby, Mississippi; Platoon Leader, Company H, 442nd Infantry Regiment, Italy, France; Company Executive Officer, 1st Student Training Regiment, Fort Benning, Georgia; Troop Executive Officer, Squadron Assistant S-3, 37th CONSTAB Squadron, Weilburg, Germany; Squadron S-1, 5th CONSTAB Regiment, Augsberg, Germany; Battalion S-1, 2nd Battalion 169th Infantry Regiment, Camp Pickett, Virginia; Division Headquarters Commandant, 43rd Infantry Division, Camp Picket, Virginia; Division Headquarters Commandant 43rd Infantry Division, Augsburg, Germany; Battalion S-3, 2nd Battalion, 169th Infantry Regiment, Hartford, Connecticut; Battalion Executive Officer, 2nd Battalion, 169th Infantry Regiment, Hartford, Connecticut; Battalion Commander, 2nd Battalion, 169th Infantry, Regiment, Hartford, Connecticut; Battle Group Executive Officer, 1st Battle Group, 43rd Division, Hartford, Connecticut; Company A Forward Support, G-1, 43rd Infantry Division, Hartford, Connecticut; Company A Forward Support, 43rd Command Headquarters, Division, Hartford, Connecticut; Support Commander, 43rd Command Headquarters, Division, Hartford, Connecticut; Brigade Commander, 43rd Brigade, 26thg Infantry Division, Hartford, Connecticut; G-1, HHD Connecticut Army National Guard, Hartford, Connecticut.