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.
2nd Garrison Division of Nanjing Military Region The 85th Division () was created on February 1949 under "the Regulation of the Redesignations of All Organizations and Units of the Army", issued by Central Military Commission on November 1, 1948, basing on the 31st Brigade, 11th Column of Huadong Field Army. Its history could be traced to 31st Brigade, 7th Column of Huazhong Field Army formed in September 1946.