I Corps

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 (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