First 1st Battalion, 1st Marines 1st Cavalry 1st Reconnaissance Battalion 1st Operations Group 1st Mounted Division 1st Regiment 1st Division 1st Fighter Brigade 1st Senate district 3rd Battalion, 1st Marines Royal 1st Devon Yeomanry 1st Rifle Division 1st Armoured Infantry Brigade (United Kingdom) 1st Word 1st Brigade Combat Team, 1st Cavalry Division (United States) 1st Pennsylvania Regiment 1st Hussars 1st Squadron, 1st Cavalry Regiment 1st Reconnaissance Squadron 1st Theater Sustainment Command 1st Marine Regiment (United States) 1st Battalion, 4th Marines 1st Brigade 2nd Battalion, 1st Marines 1st Armored Division (United States) 1st Brigade Combat Team, 1st Infantry Division (United States) 1st & Ten 1st Brigade Combat Team 1st …

Michigan Infantry Regiment 1st Artillery Regiment 1st Airborne 1st Marine Division 1st Bombardment Wing 1st Air Defense Artillery Regiment 1st Constitution Bancorp 1st Brigade (Australia) Ōita 1st district 1st Division (Thailand) 1st Missouri Infantry 1st Minnesota Infantry Regiment 1st Delaware Infantry Regiment 1st Armoured Brigade (United Kingdom) 1st Belorussian Front 1st (African) Division 1st Battle Squadron 1st Airborne Command Control Squadron 1st Armored 1st Division (Australia) 1st Infantry Division (United States) 1st Horse (Skinner's Horse) 1st Combat Engineer Battalion 1st Light Antiaircraft Missile Battalion 1st

Colorado Infantry Regiment 1st Expeditionary Rescue Group 1st Fighter Squadron 1st Canadian Parliament 1st Infantry Regiment (United States) 1st Georgia Infantry Regiment 1st millennium BC 1st Fighter Wing 1st Royal New South Wales Lancers 1st Light Car Patrol (Australia) 1st Marine Expeditionary Brigade (United States) Francis Cook, 1st Viscount of Monserrate 1st Cavalry Division (United States) 1st Source 1st (Peshawar) Division 1st Test and Evaluation Squadron 1st Anti-Aircraft Brigade 1947–48 Danish 1st Division 1st Special Operations Squadron 1949–50 Danish 1st Division 1948–49 Danish 1st Division 1st Foreign Regiment (France) 1955–56 Danish 1st Division 1st Brahmans 1