The 503rd Infantry Regiment and the 2nd Infantry Division are both formations of what military branch
2nd Infantry Division (United States) The 2nd Infantry Division ("Indianhead"; "2ID," "2nd ID", or "Second D") is a formation of the United States Army. Its current primary mission is the defense of South Korea in the initial stages of an invasion from North Korea until other American units can arrive. There are approximately 17,000 soldiers in the 2nd Infantry Division, with 10,000 of them stationed in South Korea, accounting for about 35% of the United States Forces Korea personnel.
48th Infantry Brigade Combat Team (United States) The 48th Infantry Brigade Combat Team (INF BCT) ("Macon Volunteers") is a modular infantry brigade of the Georgia Army National Guard. One of the oldest units in U.S. Army history, the lineage of the 48th Infantry Brigade can be traced back to 1825. It is one of few units in the US military that also saw service as a unit of the Confederate States of America during the American Civil War. Today, the 48th INF BCT is part of the U.S. Army's "Associated Units" program where it's aligned under the 3rd Infantry Division, a combined arms (armor, mechanized, and light infantry) combat maneuver unit of the Regular Army.