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. The regiment served as an independent regiment in the Pacific War during World War II; at Fort Campbell, Kentucky; in Okinawa, Japan; and in Germany. Regimental elements have been assigned to the 2nd Infantry Division, the 11th Airborne Division, the 24th Infantry Division, the 82nd Airborne Division, and the 173rd Airborne Brigade Combat Team. Regimental elements have participated in campaigns in the Vietnam War, Operation Enduring Freedom–Afghanistan, and Operation Iraqi Freedom. The regiment claims 15 Medal of Honor recipients: two from World War II, 10 from Vietnam, and three from Afghanistan. A parent regiment under the U.S. Army Regimental System. The regiment's 1st and 2nd Battalions are active, assigned to the 173rd Airborne Brigade, based at Caserma Ederle, Vicenza, Italy.
100th Infantry Battalion (United States) The 100th Infantry Battalion is the only infantry unit in the United States Army Reserve. In World War II, the then-primarily Nisei battalion was composed largely of former members of the Hawaii Army National Guard. The 100th saw heavy combat during World War II before and after combining with the 442nd Infantry Regiment, another mostly Nisei military unit, into a single fighting combat team. Based at Fort Shafter, Honolulu, Hawaii, the 100th Battalion has reservists from Hawaii, American Samoa, Guam and Saipan, and has deployed to Iraq and Kuwait. The unit was unofficially nicknamed the "Purple Heart Battalion", with the motto "Remember Pearl Harbor".