List of wars involving the United States in the 20th century

This is a list of military conflicts, that United States has been involved in the 20th century.

For the criteria of what may be permitted on this list, see Lists of wars involving the United States.

Key

20th-century wars

ConflictAlliesOpponent(s)Result Presidents Crazy Snake's War(1909)Part of the American Indian WarsLocation: Oklahoma Creek US victoryTheodore Roosevelt(September 14, 1901 – March 4, 1909) William Howard Taft

March 4, 1909 – March 4, 1913) Mexican Border War(1910–1919)Part of the Mexican Revolution, the Banana Wars, and World War ILocation: Mexico–United States border Supported by: US victory Seditionist insurgency suppressed Permanent border wall established Pancho Villa's troops no longer an effective fighting force Mexican Constitutionalist faction leader Venustiano Carranza recognised as the sole leaders of the Mexican government by the United StatesWilliam Howard Taft (March 4, 1909 – March 4, 1913)

Woodrow Wilson(March 4, 1913 – March 4, 1921) Little Race War(1912)Part of the Banana WarsLocation: Cuba Cuba Cuban PIC US-allied victory Dissolution of the PICWilliam Howard Taft(March 4, 1909 – March 4, 1913) United States occupation of Nicaragua(1912–1933)Part of the Banana WarsLocation: Nicaragua Nicaraguan Liberals Sandinistas US victory Change of regime in Nicaragua Great Depression marks US withdrawal (1933)William Howard Taft(March 4, 1909 – March 4, 1913)

Woodrow Wilson(March 4, 1913 – March 4, 1921)

Warren G. Harding(March 4, 1921 – August 2, 1923)

Calvin Coolidge(August 2, 1923 – March 4, 1929)

Herbert Hoover(March 4, 1929 – March 4, 1933) Bluff War(1914–1915)Part of the American Indian WarsLocation: Utah and Colorado UtePaiute US victoryWoodrow Wilson(March 4, 1913 – March 4, 1921) United States occupation of Veracruz(1914)Part of the Mexican RevolutionLocation: Mexico Supported by:

Supported by:

US victoryWoodrow Wilson(March 4, 1913 – March 4, 1921) United States occupation of Haiti(1915–1934)Part of the Banana WarsLocation: Haiti Haitian Rebels US-allied victoryWoodrow Wilson(March 4, 1913 – March 4, 1921)

Warren G. Harding(March 4, 1921 – August 2, 1923)

Calvin Coolidge(August 2, 1923 – March 4, 1929)

Herbert Hoover(March 4, 1929 – March 4, 1933)

Franklin D. Roosevelt(March 4, 1933 – April 12, 1945) United States occupation of the Dominican Republic(1916–1924)Part of the Banana WarsLocation: Dominican Republic US victoryWoodrow Wilson(March 4, 1913 – March 4, 1921)

Warren G. Harding(March 4, 1921 – August 2, 1923)

Calvin Coolidge(August 2, 1923 – March 4, 1929) World War I(1914–1918, direct U.S. involvement in 1917–1918)Location: Europe, Africa, Asia, Middle East, Atlantic Ocean, the Pacific Islands, and coast of North and South AmericaSpecific locations where the United States was involved in battles or attacks during World War I:Atlantic Ocean, Belgium, France, Italy

(from 1917)(until 1917) Sultanate of Egypt Idrisid Emirate of Asir Emirate of Nejd and Hasa Kingdom of Hejaz Republic of China Siam Allied victory American entry into World War I in 1917 First time in history, the United States sent soldiers abroad to defend foreign soil October Revolution in the Russian Republic On December 13, 1918, Woodrow Wilson arrived to France and became the first U.S. president to visit Europe while in office to take part in World War I peace negotiations The fall of the Austro-Hungarian, German and Russian empires Formation of new countries in Europe and the Middle East Transfer of German colonies and regions of the former Ottoman Empire to other powers Establishment of the League of Nations, which led to the creation of today's United Nations World War I was known as the "Great War" or simply the "World War" until the start of World War II in 1939 In August 1914, The Independent stated of the conflict, "This is the Great War. It names itself."Woodrow Wilson(March 4, 1913 – March 4, 1921) Russian Civil War(1917–1922, direct U.S. involvement in 1918–1920)Part of the Russian Revolution, the revolutions of 1917–1923 and the aftermath of World War ILocation: Russia Mountain Republic Makhnovshchina Right SRs Left SRs Green armies Czechoslovakia

Empire of Japan

Mongolia

Mongolian Communists Makhnovshchina Left SRs Green armies Bolshevik victory The October Revolution led by the Russian Communist Party of Vladimir Lenin overthrows the Russian Provisional Government of the Russian Republic and establishes the Russian Socialist Federative Soviet Republic The Red Terror and War Communism The Communist Massacre of the Russian Royal Family Around 5,000 American soldiers were part of an allied expedition American Expeditionary Force, North Russia American Expeditionary Force, Siberia Victory for the Bolshevik Red Army in Russia, parts of Ukraine and Belarus, South Caucasus, Central Asia, Tuva, and Mongolia; incorporation of those territories (except for Tuva and Mongolia which become client states) into the Russian SFSR and later Soviet Union Victory for pro-independence movements in Poland, Finland, Estonia, Latvia, Lithuania, and Poland; expulsion of Bolshevik forces from those territoriesWoodrow Wilson(March 4, 1913 – March 4, 1921)Turkish War of Independence(U.S. involvement)(1919–1922)Part of the Revolutions of 1917–1923 in the aftermath of World War I and the Greco-Turkish War (1919–1922)Location: TurkeyAllied powers: French West AfricaWestern Society for French History. Meeting: Proceedings of the ... Annual Meeting of the Western Society for French History, New Mexico State University Press, 1996, sayfa 206 . Armenian Legion Algeria Morocco Tunisia

Briton Cooper Busch: Mudros to Lausanne: Britain's Frontier in West Asia, 1918–1923, SUNY Press, 1976, , sayfa 216 ."British Indian troops attacked by Turks; thirty wounded and British officer captured – Warships' guns drive enemy back ," New York Times (18 June 1920)."Allies occupy Constantinople; seize ministries; Turkish and British Indian soldiers killed in a clash at the War Office ," New York Times (18 March 1920). Japan

Istanbul Government Other pro-Istanbul rebels

Separatists: Pontic Greek rebels Kurdish rebels Assyrian rebels Green ArmyTurkish Nationalists:Turkish victory Indirect U.S. involvement The fall of the Ottoman Empire Treaty of Lausanne Establishment of the Republic of Turkey Chester concession Abolition of the Caliphate Declaration of Amnesty ending the Prosecution of Ottoman war criminals for the Armenian, Greek, and Assyrian genocidesWoodrow Wilson(March 4, 1913 – March 4, 1921)

Warren G. Harding(March 4, 1921 – August 2, 1923) Posey War(1923)Part of the American Indian WarsLocation: Utah UtePaiute US victory Last Indian uprisingWarren G. Harding(March 4, 1921 – August 2, 1923) Attack on the US embassy during the Fall of Addis Ababa(1936)Part of the Second Italo-Ethiopian WarLocation: Ethiopia

Supported by: Ethiopian civilians Ethiopian rioters US-allied victory Chaos erupted in Addis Ababa after Ethiopia's emperor Haile Selassie I fled following the Italian victory in the Second Italo-Ethiopian War Armed rioters surrounded the embassy, trapping American diplomats, U.S. Navy radio operators, and dozens of refugees inside The entire defense fell on 12 people: Diplomat Cornelius Van Hemert Engert, his wife, six diplomatic staff and four U.S. Navy radio operators The Navy operators kept communications alive, sending urgent SOS updates to Washington while under constant gunfire Running out of ammunition, the entire American group was successfully evacuated by British troops U.S. government closed its diplomatic mission in Addis Ababa a few months laterFranklin D. Roosevelt(March 4, 1933 – April 12, 1945)USS Panay incident(1937)Part of the Second Sino-Japanese War, Battle of Nanking, and the Yangtze PatrolLocation: China Inconclusive/Other Result U.S. servicemen attempted to return fire on their machine guns to ineffective results Japan forced to pay war reparationsFranklin D. Roosevelt(March 4, 1933 – April 12, 1945) World War II(1939–1945, direct U.S. involvement in 1941–1945)Location: Europe, Pacific Ocean, Atlantic Ocean, Southeast Asia, East Asia, Middle East, Mediterranean, North Africa, Oceania, North and South AmericaSpecific locations where the United States was involved in battles or attacks during World War II:Algeria, Aruba, Atlantic Ocean, Australia, Austria, Bay of Biscay, Belgium, Bering Sea, Bismarck Sea, Bosnia and Herzegovina, Brunei, Bulgaria, Burma, Caribbean Sea, China, Christmas Island, Coral Sea, Croatia, Czech Republic, East China Sea, Egypt, Federated States of Micronesia, France, Germany, Greenland, Gulf of Mexico, Hong Kong, Hungary, Iceland, Indonesia, Italy, Japan, Java Sea, Kiribati, Libya, Luxembourg, Malaysia, Malta, Manchukuo, Marshall Islands, Mediterranean Sea, Montenegro, Morocco, Nauru, Netherlands, Norway, Pacific Ocean, Palau, Papua New Guinea, Philippines, Philippine Sea, Poland, Romania, Serbia, Singapore, Slovakia, Solomon Islands, Solomon Sea, South China Sea, Soviet Union, Switzerland, Taiwan, Thailand, Timor-Leste, Tunisia, United States (Alaska, Guam, Hawaii, Midway Atoll, Northern Mariana Islands, Wake Island) Allies:

and others (from 1941)(from 1941) Kingdom of the South(from 1943) Czechoslovak Republic Republic of Cuba(from 1945) Republic of Haiti Brazil (from 1943) Sultanate of Muscat and Oman(until 1944) Korean Provisional Government Axis: (until 1943)(from 1943)(until 1944)(until 1944)(until 1944)(until 1944) Hellenic State Quisling's Norway RNG China Empire of Vietnam Kingdom of Luang Prabang Kingdom of Kampuchea

Non-Axis: (until 1941) US-allied victory The end of America's isolationism after attack on Pearl Harbor in 1941 The United States was first referred to as a superpower in 1944 In July 1945, the United States conducted the first nuclear test, and one month later became the first and only country to use nuclear weapons in war Collapse of Nazi Germany The fall of Japanese Empire and Italian Empire End of Fascism in Europe and Japanese militarism in Asia–Pacific Emergence of the United States and the Soviet Union as rival superpowers until dissolution of the Soviet Union The Iron Curtain separated Eastern and Western Europe(1945–1991) Allied Occupation of Germany(1945–1949) American occupation zone in Germany Allied Occupation of Austria(1945–1955) U.S. Occupation of Japan(1945–1952) U.S. Occupation of Korea(1945–1948) U.S. Army Military Government in Korea Creation of the United Nations Creation of the NATO Creation of the European Coal and Steel Community, which led to the creation of today's European Union Beginning of the Atomic Age Beginning of the Cold War(1947–1991)Franklin D. Roosevelt(March 4, 1933 – April 12, 1945)

Harry S. Truman(April 12, 1945 – January 20, 1953)Operation Beleaguer(1945–1949)Part of the Chinese Civil War and the Cold WarLocation: Hebei and Shandong provinces, China Chinese Communist Party Inconclusive/Other Result U.S. withdrawal from China Japanese and Korean soldiers successfully disarmed and repatriated Subsequent communist victoryHarry S. Truman(April 12, 1945 – January 20, 1953)Greek Civil War(1946–1949)Part of the Cold WarLocation: Greece Kingdom of Greece

Supported by: Provisional Democratic Government

Supported by: People's Republic of Bulgaria US-allied victory The Greek government, heavily supported by the United States defeated the communist Democratic Army of Greece, preventing a communist takeover Indirect U.S. involvement The U.S., particularly through the CIA, engaged in intelligence gathering and covert efforts to bolster anti-communist forces American military advisors were sent to Greece to train, reorganize, and provide tactical guidance to the Greek armed forces The U.S. provided hundreds of millions of dollars in financial assistance and a continuous flow of weapons, aircraft, equipment, and supplies