The 503rd Infantry Regiment and the 2nd Infantry Division are both formations of what military branch
503rd Infantry Regiment (United States): The 503rd Infantry Regiment, formerly the 503rd Parachute Infantry Regiment (PIR) and the 503rd Airborne Infantry Regiment (AIR), is an airborne infantry regiment of the United States Army. 2nd Infantry Division (United States): The 2nd Infantry Division ("Indianhead"; "2ID," "2nd ID", or "Second D") is a formation of the United States Army.
United States Army