The 504th Infantry Regiment, originally the 504th Parachute Infantry Regiment (504th PIR), is an airborne forces regiment of the United States Army, part of the 82nd Airborne Division, with a long and distinguished history. The regiment was first formed in mid-1942 during World War II as part of the 82nd Airborne Division and saw service in Sicily, Italy, Anzio, the Netherlands, Belgium and Germany.