History of War

IN THE 20TH CENTURY

 

Wars not covered on main timeline

1898-1901: Boxer Rebellion (Northern China)
1898-1934: Banana Wars (Central America)
1899-1902: Second Anglo-Boer War (South Africa)
1903-1907: Saudi-Rashidi War (Qassim region, Arabia)
1904-1905: Russo-Japanese War (Manchuria & Korea)
1904-1907: Herero War (German South-West Africa)
1904-1908: Macedonian Struggle (Greek Macedonia)
1909-1911: Ouaddai War (Modern Sudan/Chad)
1912-1913: First and Second Balkan Wars (The Balkans)
1912-1916: Contestado War (Southern Brazil)
1919-1921: Polish-Soviet War (Poland)
1935-1936: Second Italo-Ethiopian War (Ethiopia)

1936-1939: Arab Revolt in Palestine
1937-1945: Second Sino-Japanese War (China & Burma)

1945-1954: Indonesian National Revolution
1946-1954: First Indochina War (Veitnam, Laos, & Cambodia)
1960-1996: Guatemalan Civil War
1961-1974: Portguese Colonial War (Angola, Guinea, & Mozambique)
1964-1974: Rhodesian-Bush War (Rhodesia, Zambia, Mozambique)
1966-1989: South Africa Border War (South Africa - Namimbia & Angola)

1975-1990: Lebanese Civil War

1975-2002: Angolan Civil War

1977-1991: Cambodian- Vietnamese War

1990-1993: Rwandan Civil War

1996-1997: First Congo War

Overall Timeline of War in the 20th Century (1900-2000)

Interactive version | Text-only version

Main Timeline

Timeline guidelines
Hover over selected war on timeline to see its description, and to see where it occured and what countries were involved on the world map below. Gray wars are wars not covered in-depth on this site. Wars coloured in red, on the other hand, are covered in-depth as major sections of this site. Click the red links to go to the overview pages of those particular wars.

Russian Revolution of 1905
A wave of mass social and political revolt against the Russian empire by Russian Revolutionaries. This conflict consisted of workers strikes, peasant unrest, military mutinies and led to the establishment of a limited constitutional monarchy, as a last attempt by the Tsar to maintain his regime.
Mexican Revolution (1910-1922)
A major armed conflict between revolutionary forces and the autocratic government led by long-time dictator, Porfirio Diaz. After 11 years of fighting, Diaz was eventually removed from power and exiled to France. Meanwhile, the revolution led to creation of the Partido Nacional Revolucionario ("National Revolutionary Party") in 1929, which itself monopolized power throughout much of the 20th century.
World War I (1914-1918)
Also known as the Great War or the First World War, World War I was the largest military conflict to date, both in terms of lives lost and countries involved. Nearly the entire planet was involved in some capacity, whether it was military or economic support, however, most of the war centred around Europe, particularly the area surrounding the German and Austrian-Hungarian borders, known as the Eastern and Western Fronts. To learn more, click to go to the full section on WWI.
Russian Civil War (1917-1923)
Following the Revolution of 1917, the Russian Civil War was fought mostly between the Red Army, the socialist Bolsheviks and the loosely allied White Army, represented by various monarchist, capitalist, and alternate socialist parties. The conflict was eventually resolved when the Red Army defeated the White Army in the Ukraine and the countries, Finland, Estonia, Latvia, Lithuania, and Poland were established as sovereign states, and the rest of Russian empire was consolidated as the Soviet Union.
Irish War of Independence (1919-1921)
After a landslide victory of the Irish Republican party in 1918, tensions rose between Irish nationalists, the Irish Republic Army (IRA) and British security forces in Ireland. This conflict was considered a guerrilla war and resulted in the independence of Southern Ireland from the British Empire, while Northern Ireland remained a part of the United Kingdom.
Turkish War of Independence (1919-1923)
Following the defeat, occupation, and partitioning of the Ottoman Empire by Entente forces in World War I, Turkish nationalists fought against proxy armies of the Entente armies in this War of Independence. This included Greece on the Western Front, Armenia on the Eastern Front, and France on the Southern Front, among other Entente forces. The Turkish Nationalists won by a decisive victory and overthrew the Ottoman sultanate.
Chinese Civil War (1927-1949)
The Chinese Civil War was fought between the Kuomintang party-led forces from the Republic of China government and forces loyal to the Communist Party of China (CPC). These two forces united during World War II to fight against Japanese invasion but resumed fighting afterwards, which continued until 1949, when two independent states were established, the Republic of China (ROC) in Taiwan and the People’s Republic of China (PRC) in mainland China. To this day, no peace treaty between these two parties has been signed.
Spanish Civil War (1936-1939)
Sometimes referred to as the dress rehearsal for World War II, the Spanish Civil War was fought between the Republicans, loyal to the democratic Spanish government, supported by the Soviet Union and Mexico, and the Nationalists, fascist rebels, supported by Nazi Germany, Fascist Italy, and Portugal. The war began after a rebel coup of the leftist Republican government was only partially successful and a resulting battle for the control of the country ensued and ended with a decisive Nationalist victory. Spain’s neutral status in World War II was largely due to the instability of the country at the time.
World War II (1939-1945)
In many ways, a continuation of the First World War, World War II again involved nearly every country in the world, with very few countries remaining neutral. It is still the largest military conflict to date and was fought in four major locations or theatres, the Western European Theatre, the Eastern European Theatre, the Pacific Theatre in Eastern Asia, and the Middle-Eastern/Mediterranean, which also included several battles in Africa. To learn more, click to visit to the full section on WWII.
Greek Civil War (1946-1949)
Following World War II, this conflict was fought between Greek government Army, supported by the United States and Great Britain, and the Democratic Army of Greece (DSE), a military arm of the Greek Communist Party (KKE), supported by Yugoslavia, Albania, and Bulgaria. The Greek government Army defeated the insurgents in this politically polarizing war that is often considered the first major conflict of the Cold War.
The Cold War (1947-1991)
The Cold War was an era of of social, political, and military tension between the Soviet Union and its Warsaw Pact allies and the United States and its NATO allies. While neither country engaged in full-scale military attacks, there were several major regional military conflicts and both countries armed themselves for a full-scale nuclear world war. The Cold War eventually ended in 1991, once its Warsaw Pact Allies started fighting for independence and its economic infrastructure crumbled. To learn more, click to visit to the full section on the Cold War.
1948 Arab-Israeli War (1948-1949)
A war fought between the State of Israel and Arab-Palestinian forces from Palestine, Egypt, Jordan, Syria, Iraq, and Lebanon, with volunteer support from Sudan, and Yemen over the territory determined by the UN Partition Plan, that ruled Palestine would be divided into three territories: a Jewish state (Israel), an Arab state (Palestine), and an International Regime for the City of Jerusalem. The war ended in an Israeli victory, annexation of 50% of the Arab state, Jordanian occupation of the West Bank and Egyptian occupation of the Gaza strip.
Korean War (1950-1953)
One of the major regional military conflicts of the Cold War, the Korean War was fought between the Soviet/Chinese-supported North Korean forces and the American/British/Turkish-supported South Korean forces. After the division of the country following World War II, tensions had risen and both countries fought for control of Korea. The conflict ended in a military stalemate, and the creation of a de-militarized zone between the two countries’ borders. To learn more, click to visit to the full section on the Korean War.
Mau Mau Uprising (1952-1960)
The Mau Mau Uprising took place in Kenya and was a revolt against colonialist British forces by the Kikuyu-dominated Mau Mau rebels. The result of the conflict was a decisive British victory due to lack of total nation support and far-superior military strength, killing between 12,000-20,000 Kenyans.
Cuban Revolution (1953-1959)
An armed revolt against the Republican Cuban government led by communist rebel leader Fidel Castro. Castro’s forces were called the 26th of July Movement and overthrew the government, forcing the American support troops to leave the country. This event resulted in a trade and tourism embargo with the United States that is only slowly being reformed today, since Castro’s brother has taken place as the leader of the Cuban government.
Algerian War (1954-1962)
Also known as the Algerian War of Independence, this military conflict involved French colonialists and Algerian loyalists against Algerian independence forces called the National Liberation Front (FLN). This war was characterized by its guerrilla warfare, terrorist strategy, torture on both sides, and counter-terrorism operations. The result of the war was a victory for the FLN and consequently a mass of European Algerians immigrated to France, fearing the FLN’s brutal revenge.
Vietnam War (1955-1975)
Also known as the American-Vietnam War or the Second Indochina War, the Vietnam War was a conflict fought between American troops and their South Vietnamese allies against North Vietnamese communist forces, supported economically and politically by the Soviet Union and China. The Vietnam War was one of the major proxy wars of the Cold War and one of the most polarizing wars for the American people. The war eventually resulted in a North Vietnamese victory. To learn more, click to visit to the full section on the Vietnam War.
Bay of Pigs Invasion (1961)
A direct response to the Cuban Revolution and Fidel Castro’s ascension as communist leader of Cuba, the Bay of Pigs Invasion was a failed CIA operation executed by the American military to overthrow Castro’s government. The Cuban military defended their country from invasion and after three days of fighting, the American forces retreated, which only strengthened Castro’s position as a dictator, as well as his ties with the Soviet Union. This event was in many ways a precursor to the Cuban Missile Crisis of 1962.
Soviet War in Afghanistan (1979-1989)
The last of the major proxy wars of the Cold War, the Soviet War in Afghanistan was fought between the Soviet-backed Afghanistan Republic and several different insurgent forces trained in Pakistan, China, and Iran, known as a whole as the Mujahideen. Heavily backed financially by the United States and Saudi Arabia, the the Mujahideen were very successful and the war ended in a military withdrawal by the Soviet Union. To learn more, click to visit to the full section on the Soviet War in Afghanistan.
Iran/Iraq War (1980-1988)
After a long history of border disputes, the Iran-Iraq war began in 1980 when Iraq invaded Iran following the Iranian Revolution of 1979, which the Iraqi government believed would inspire insurgency among Iraq’s long suppressed Shia majority. After initially gaining territory in Iran, Iraqi forces were quickly repelled by 1982 and the Iranians went on the offensive. Fighting continued for the next six years and involved the use of chemical weapons and trench warfare, but eventually ended in a UN-brokered cease-fire in 1988, and no border changes.
Falklands War (1982)
The Falklands War was a 10-week military conflict in 1982 between Argentina and the United Kingdom over two British islands in the South Atlantic, known as the Falklands, that began after Argentina invaded and occupied the islands that it had long claimed sovereignty over. The conflict ended with an Argentine surrender after the British forces engaged in a joint Naval and Air Force attack on the islands.
Gulf War (1990-1991)
The Gulf War, codenamed Operation Desert Storm and Desert Shield, by the American government was an American led-coalition in response to Iraq’s invasion and annexation of Kuwait. With the largest military alliance since World War II, the Gulf War ended within a year, and resulted in the removal of Iraqi troops from Kuwait and a military cease-fire. The Gulf War also marked the introduction of live news broadcasts into front lines of battle, especially by CNN.
Croatian War of Independence (1991-1995)
Following the declaration of independence from the Socialist Federal Republic of Yugoslavia (SFRY) by the Croatian government, the Croatian War of Independence began when the Yugoslav People’s Army (JNA) violently opposed this declaration. After Serbian-led opposition forces failed to occupy the whole country, they established the Republic of Serbian Krajina (RSK) within Croatia in 1992 and the next three years consisted of intermittent fighting before Croatia finally solidified its victory and independence in 1995.
Bosnian War (1992-1995)
Following the Croatian and Slovenian secessions from the Yugoslavian Republic (SFRY), Bosnia & Herzegovina passed a referendum for independence in 1992. Bosnian Serbs aided by the Yugoslav People’s Army rejected the declaration, and fought Bosnian nationalist forces, however, soon Croat forces were fighting as well, looking to regain more territory from Bosnia & Herzegovina. The conflict ended in 1995 with a Bosnian nationalist victory, more than 100,000 deaths, and acted as further dissolution of the Yugoslavian Republic.
Kosovo War (1998-1999)
A conflict that involved fighting between the Federal Republic of Yugoslavia (SFRY), which occupied Kosovo at the time, and a Kosovo-Albanian rebel group called the Kosovo Liberation Army (KLA), along with air support from NATO and ground support from the Albanian Army. The war ended with a KLA victory and the signing of the Kumanovo Treaty, which granted Kosovo its independence.

 

 

World Map

Disclaimer: It must be noted that there are still hundreds of wars and minor military conflicts not covered by either of these timelines. The wars included on this site were selected based on the amount of casualties, their length, and their political significance, especially in relation to World War I, World War II, and the Cold War, since these are the conflicts that are the main focus of this website. For this reason, the amount of South American, African, and Middle-Eastern wars included in these lists are not as comprehensive as European conflicts and those that have involved the United States or the Soviet Union.