I Corps, 1st Corps, or First Corps may refer to:

France

  • 1st Army Corps (France)
  • I Cavalry Corps (Grande Armée), a cavalry unit of the Imperial French Army during the Napoleonic Wars
  • I Corps (Grande Armée), a unit of the Imperial French Army during the Napoleonic Wars

Germany

  • I Cavalry Corps (German Empire), a unit of the Imperial German Army
  • I Corps (German Empire), a unit of the Imperial German Army
  • I Reserve Corps (German Empire), a unit of the Imperial German Army
  • I Royal Bavarian Corps, a unit of the Bavarian Army and the Imperial German Army
  • I Royal Bavarian Reserve Corps, a unit of the Bavarian Army and the Imperial German Army
  • I Army Corps (Wehrmacht), a unit in World War II
  • I SS Panzer Corps, a unit in World War II

India

  • I Corps (British India)
  • I Corps (India)

Russia and Soviet Union

  • 1st Army Corps (Russian Empire)
  • 1st Guards Assault Aviation Corps
  • 1st Guards Mechanized Corps (Soviet Union)
  • 1st Airborne Corps (Soviet Union)
  • 1st Army Corps (Armed Forces of South Russia), a unit in the Russian Civil War
  • 1st Army Corps (Soviet Union)
  • 1st Assault Aviation Corps
  • 1st Cavalry Corps (Russian Empire)
  • 1st Rifle Corps, Soviet Union

United Kingdom

  • I Corps (United Kingdom)
  • I Airborne Corps (United Kingdom)
  • 1st Suffolk Artillery Volunteer Corps

United States

  • I Corps (United States)
  • I Amphibious Corps
  • I Armored Corps (United States)
  • I Corps (Union Army)
  • First Corps, Army of Northern Virginia
  • First Corps, Army of Tennessee
  • First Army Corps (Spanish-American War)
  • I Field Force, Vietnam

Others

  • I ANZAC Corps, Australia and New Zealand
  • I Corps (Australia)
  • I Corps (Belgium)
  • I Corps (Bosnia and Herzegovina)
  • I Canadian Corps
  • I Corps (Czechoslovakia)
  • Finnish I Corps
  • I Corps (Continuation War)
  • I Corps (Winter War)
  • I Army Corps (Greece)
  • I Corps (North Korea)
  • I Corps (Ottoman Empire)
  • I Corps (Pakistan)
  • I Corps (Sri Lanka)
  • Polish I Corps (disambiguation), several units
  • 1st Territorial Army Corps (Romania)
  • I Corps (South Korea)
  • I Corps (South Vietnam)
  • 1st Corps (Syria)
  • 1st Corps (Vietnam People's Army)
  • 1st Corps (Yugoslav Partisans), during World War II

See also

  • List of military corps by number
  • 1st Army Corps (disambiguation)
  • 1st Army (disambiguation)
  • 1st Brigade (disambiguation)
  • 1st Division (disambiguation)
  • 1st Regiment (disambiguation)
  • 1 Squadron (disambiguation)