Major Wars from the 20th and 21st Century

modern wars

The 20th and 21st centuries witnessed numerous significant conflicts that have shaped global politics, economies, and societies. These wars, often involving multiple nations, have varied in causes, scope, and duration. The examination of these conflicts provides insight into:

  • The geopolitical shifts.
  • The advancements in military technology.
  • The human cost and societal changes.
  • The development of international relations and laws.

Understanding these major wars is crucial for comprehending current global dynamics and anticipating future conflicts. This article explores pivotal wars from the World Wars to more recent engagements, highlighting their impact on a global scale.

Boxer Rebellion (1900-1901)

The Boxer Rebellion, also known as the Boxer Uprising, took place in China between 1900 and 1901. The uprising was a violent anti-foreign, anti-colonial, and anti-Christian insurrection.

  • The Boxers aimed to expel foreign powers and missionaries from China.
  • The movement was named after the “Boxers,” who practiced martial arts.
  • They attacked foreign embassies and murdered foreigners and Chinese Christians.
  • An Eight-Nation Alliance, including Japan, Russia, Britain, France, the U.S., Germany, Italy, and Austria-Hungary, intervened.
  • The rebellion was suppressed by the alliance in 1901.
  • The Qing Dynasty’s authority was further weakened, leading to significant political changes in China.

Philippine-American War (1899-1902)

The Philippine-American War marked the struggle between the First Philippine Republic and the United States. It followed the latter’s acquisition of the Philippines from Spain after the Spanish-American War. Key details include:

  • Conflict Duration: February 4, 1899 – July 2, 1902
  • Main Combatants: Filipino revolutionaries and American forces
  • Initial Hostilities: Began with the Battle of Manila
  • Significant Battles:
    • Battle of Manila
    • Battle of Tirad Pass
    • Battle of Pulang Lupa
  • Casualties: Estimated between 200,000 – 1,500,000, including civilian losses due to combat, famine, and disease
  • Outcome: U.S. establishment of control over the Philippines

“I am writing to inform you that the Filipino people must have independence. This is our goal and it will remain our goal.”

South African War (1899-1902)

The South African War, also known as the Second Boer War, was fought between the British Empire and the two Boer republics: the South African Republic (Transvaal) and the Orange Free State. Lasting from October 11, 1899, to May 31, 1902, this conflict centered on Britain’s control in Southern Africa.

Main Reasons:

  • Discovery of gold and diamonds in the Boer territories.
  • British imperialism.

Key Battles:

  • Battle of Colenso
  • Siege of Mafeking
  • Battle of Spion Kop


  • British victory
  • Treaty of Vereeniging
  • Incorporation of Boer republics into the British Empire


  • Transition to British colonial rule
  • Long-term ethnic tensions

Russo-Japanese War (1904-1905)

The Russo-Japanese War occurred between 1904 and 1905. This conflict showcased the rise of Japan as a formidable military power.

  • Causes:
    1. Rival ambitions in Korea and Manchuria.
    2. Russian expansionism in Asia.
  • Major Battles:
    1. Battle of Port Arthur.
    2. Battle of Tsushima.
  • Consequences:
    1. Treaty of Portsmouth.
    2. Shift in power dynamics showing Japan’s strength.

The war marked the first major victory in modern times of an Asian power over a European one. It had significant impacts on both nations and influenced global politics.

Mexican Revolution (1910-1920)

The Mexican Revolution began in 1910 as a response to the long-standing dictatorship of Porfirio Díaz. It aimed to address widespread social injustices, land reforms, and labor rights. Key figures included:

  • Francisco Madero: Advocated democratic reforms.
  • Emiliano Zapata: Fought for land reforms with his slogan, “Land and Liberty.”
  • Pancho Villa: Led various revolutionary battles in Northern Mexico.
  • Venustiano Carranza: Eventually became the Mexican President aiming to establish a new constitution.

The revolution led to the 1917 Constitution, influencing labor laws, property rights, and helped shape modern Mexican society.

World War I (1914-1918)

World War I, also known as the Great War, marked a significant global conflict.


  • The assassination of Archduke Franz Ferdinand.
  • Complex alliance systems.
  • Nationalism, imperialism, and militarism.

Major Powers:

  • Allied Powers: France, the United Kingdom, Russia, Italy, the United States.
  • Central Powers: Germany, Austria-Hungary, the Ottoman Empire, Bulgaria.

Key Battles:

  • Battle of the Somme.
  • Battle of Verdun.
  • Battle of Gallipoli.


  • Treaty of Versailles.
  • Redrawing of European borders.
  • Heavy casualties and economic consequences.
  • Foundations for World War II.

Russian Civil War (1918-1922)

The Russian Civil War was a significant conflict that erupted after the Russian Revolution of 1917.

  • Combatants: Primarily between the Red Army (Bolsheviks) and the White Army (anti-Bolshevik forces).
  • Key Figures:
    • Vladimir Lenin
    • Leon Trotsky
    • Admiral Alexander Kolchak
  • Major Events:
    • Treaty of Brest-Litovsk (1918)
    • Red Terror
    • Siberian Campaign (1918)
  • Consequences:
    • Bolshevik victory
    • Creation of the Soviet Union (1922)
    • Substantial loss of life and economic hardship
  • International Involvement: Allied intervention, including forces from the UK, USA, France, and Japan.

The war drastically reshaped Russia’s political, social, and economic landscape.

Italo-Turkish War (1911-1912)

The Italo-Turkish War was fought between the Kingdom of Italy and the Ottoman Empire. This conflict occurred in North Africa (modern-day Libya), where Italy sought to establish a colonial foothold.

Key Points:

  • Duration: It lasted from September 29, 1911, to October 18, 1912.
  • Major Battles:
    • Battle of Tripoli
    • Battle of Zawiya
  • Military Achievements:
    • Italy employed aircraft for reconnaissance and bombing, marking the first use of aviation in war.
  • Outcomes:
    • Concluding with the Treaty of Ouchy, resulting in Italy gaining control of Tripolitania, Fezzan, and Cyrenaica.
  • Legacy:
    • The war prompted reforms in the Ottoman military and revealed weaknesses within the Empire.

Chaco War (1932-1935)

The Chaco War was a conflict between Bolivia and Paraguay over the Chaco Boreal region.


  • Dispute over the Chaco Boreal territory.
  • Belief that the region harbored oil reserves.
  • National pride and territorial ambitions.

Key Events:

  1. Initial Clashes (1932):
    • Skirmishes began in June 1932.
    • Bolivians attacked Paraguayan outposts.
  2. Major Battles:
    • Battle of Boquerón (1932).
    • Battle of Campo Vía (1933).
  3. Stalemate and Attrition:
    • Harsh conditions led to high casualties.
    • Guerrilla tactics and trench warfare.


  • Paraguay emerged victorious.
  • Bolivia suffered heavy losses.
  • Treaty of Peace (1938) delineated borders.


  • Significant loss of life on both sides.
  • Economic and political destabilization.
  • National identities and military reforms.

Italo-Ethiopian War (1935-1936)

The Italo-Ethiopian War, also known as the Second Italo-Ethiopian War, occurred from October 1935 to May 1936. This conflict saw Italy, led by Benito Mussolini, invade Ethiopia, seeking to expand its colonial empire.

Key Events:

  • Invasion: Italy invaded Ethiopia on October 3, 1935.
  • Advanced Weaponry: Italy used modern weaponry, including chemical weapons.
  • League of Nations: Ethiopia appealed to the League of Nations, but sanctions were ineffective.
  • Fall of Addis Ababa: On May 5, 1936, Italian forces captured Ethiopia’s capital, Addis Ababa.
  • Occupation: King Haile Selassie fled into exile, and Italy proclaimed Ethiopia part of Italian East Africa.

Spanish Civil War (1936-1939)

The Spanish Civil War occurred between 1936 and 1939. It pitted the Republicans, who were left-leaning and supported the elected government, against the Nationalists, led by General Francisco Franco.

  • Republicans:
    • Included communists, socialists, and anarchists
    • Received support from the Soviet Union and International Brigades
  • Nationalists:
    • Comprised conservatives, monarchists, and fascists
    • Backed by Nazi Germany and Fascist Italy

Key events:

  1. 1936: Nationalists launch coup
  2. 1937: Bombing of Guernica
  3. 1939: Nationalist victory, Franco’s dictatorship begins

Casualties were high, resulting in mass suffering.

World War II (1939-1945)

World War II was a global conflict involving over 30 countries and resulting in significant changes worldwide. Key events include:

  • Invasion of Poland: Germany’s invasion in 1939, which triggered the war.
  • Pearl Harbor: Japan’s attack on the US naval base in 1941, leading to America’s entry into the war.
  • D-Day: The 1944 Allied invasion of Normandy.
  • Hiroshima and Nagasaki: The 1945 atomic bombings by the United States.

The conflict saw unprecedented levels of destruction and genocide, including the Holocaust, which led to the deaths of six million Jews.

Korean War (1950-1953)

The Korean War was a conflict between North Korea, backed by China and the Soviet Union, and South Korea, supported primarily by the United States and other United Nations member nations.

  • Inception: June 25, 1950, with North Korea’s invasion of South Korea.
  • Major Battles:
    • Battle of Osan
    • Battle of Inchon
    • Battle of Pusan Perimeter
  • Stalemate: By July 1951, the war had reached a stalemate.
  • Armistice Agreement: Signed on July 27, 1953, establishing the Korean Demilitarized Zone (DMZ).
  • Casualties: Approximately 2.5 million military and civilian lives were lost.

The war significantly impacted Korean peninsula geopolitics and Cold War dynamics.

Vietnam War (1955-1975)

The Vietnam War involved North Vietnam and its communist allies fighting against South Vietnam and its principal ally, the United States.

  • 1955: Beginning of the conflict, with political tension escalating in Vietnam.
  • 1964: Gulf of Tonkin Incident led to increased U.S. military involvement.
  • 1968: The Tet Offensive marked a significant turning point, rattling U.S. public opinion.
  • 1973: Paris Peace Accords were signed, leading to the withdrawal of U.S. troops.
  • 1975: Fall of Saigon saw the end of the war and unification of Vietnam under communist control.

The war had profound effects on both Vietnamese and American societies.

Six-Day War (1967)

The Six-Day War, fought between June 5 and June 10, 1967, saw Israel battling Egypt, Jordan, and Syria. This conflict fundamentally altered Middle Eastern geopolitics.

  • Background: Rising tensions between Israel and neighboring Arab countries.
  • Key Events:
    • June 5: Israel launched preemptive air strikes destroying 90% of Egypt’s air force.
    • June 6: Ground offensives began on multiple fronts.
    • June 7: Israeli forces captured East Jerusalem from Jordan.
    • June 9-10: Israel expanded into the Golan Heights, controlling strategic points.
  • Results:
    • Israel’s territorial gains included the Gaza Strip, West Bank, Sinai Peninsula, and Golan Heights.
    • Significant shift in regional power dynamics.

The swift and decisive nature of the conflict marked a turning point in regional history.

Yom Kippur War (1973)

In October 1973, Egypt and Syria launched a surprise attack on Israel. The conflict began on Yom Kippur, the holiest day in Judaism. The war lasted for 19 days, causing significant casualties on both sides.

  • Combatants: Egypt, Syria, and Israel
  • Casualties:
    • Israeli military: Over 2,500 killed
    • Arab coalition: Around 15,000 killed

Fought across the Sinai Peninsula, Golan Heights, and surrounding regions, it resulted in military and territorial changes. The war led to a temporary oil embargo by the Arab states, causing a global energy crisis.

Afghan War (1978-1992)

The Afghan War, also known as the Soviet-Afghan War, began in 1978 and continued until 1992. This war saw:

  • Soviet Union invading Afghanistan in 1979 to support the communist government.
  • Mujahideen, Afghan resistance fighters, opposing the Soviet forces.
  • The use of guerrilla warfare by Mujahideen, heavily funded by the United States and other nations.
  • The conflict causing significant civilian casualties and displacement.
  • The war contributing to the eventual dissolution of the Soviet Union.
  • The withdrawal of Soviet troops in 1989, leading to internal strife.
  • The war ending in 1992 with the fall of the Afghan government.

Iran-Iraq War (1980-1988)

The Iran-Iraq War, also known as the First Persian Gulf War, commenced on September 22, 1980. Iraqi forces, led by Saddam Hussein, invaded Iran, seeking territorial gains. The conflict lasted eight years, involving extensive trench warfare and chemical weapons.

Causes and Prelude

  • Border disputes
  • Religious schisms
  • Saddam Hussein’s ambition

Major Events

  • Operation Karbala: Iran’s counter-offensive
  • Tanker War: Attacks on oil tankers
  • Use of chemical weapons by Iraq


  • Heavy casualties: Over a million dead
  • Economic distress: Both nations
  • Political ramifications: Regional power shift

Hostilities ended on August 20, 1988, with a UN-brokered ceasefire.

Gulf War (1990-1991)

The Gulf War, rooted in Iraq’s invasion of Kuwait on August 2, 1990, triggered a global response.

Key Events

  • Operation Desert Shield: Coalition forces’ defensive stance post-invasion.
  • Operation Desert Storm: Commenced January 17, 1991, marked the start of the air and missile campaign.
  • Ground Assault: Initiated on February 24, 1991, leading to a decisive Coalition victory in just 100 hours.

Key Players

  • Iraq: Led by Saddam Hussein, aiming to gain control over Kuwait.
  • Coalition Forces: Led by the United States, involving 35 nations, opposed Iraq’s aggression.


  • Kuwait liberated, significant Iraqi losses.
  • Environmental impact from oil fires and spills.
  • Heightened U.S. presence in the Middle East.

Bosnian War (1992-1995)

The Bosnian War erupted in 1992 following the breakup of Yugoslavia. Ethnic tensions among Bosniaks, Croats, and Serbs escalated.

  • Bosnian Serbs aimed to create a Greater Serbia.
  • Bosniaks sought a mult-ethnic Bosnia and Herzegovina.
  • Croats desired either independence or closer ties with Croatia.

The conflict was one of the deadliest in Europe since WWII.

  • Over 100,000 people were killed.
  • Millions were displaced.

Ethnic cleansing and war crimes, including the Srebrenica massacre, were rampant. NATO intervened in 1995, leading to the Dayton Agreement, which ended the war and established a power-sharing government in Bosnia.

Kosovo War (1998-1999)

The Kosovo War involved tension between ethnic Albanians and Serbs around the region of Kosovo.

  • Key Players: The conflict saw involvement from the Federal Republic of Yugoslavia (Serbia and Montenegro) and the Kosovo Liberation Army (KLA), with NATO later intervening.
  • Background: Ethnic tensions escalated due to historical grievances and rising nationalism.
  • Conflict: The war began in February 1998, marked by violent repression by Yugoslav forces against the Albanian population.
  • NATO Intervention: In March 1999, NATO launched airstrikes to push back Yugoslav forces.
  • Outcome: The war ended in June 1999 with a UN-led peace process and NATO presence to ensure stability.

“War does not determine who is right – only who is left.” – Bertrand Russell

War in Afghanistan (2001–2021)

In response to the September 11 attacks, the United States led an invasion of Afghanistan to dismantle al-Qaeda and remove the Taliban from power. Key events include:

  • Operation Enduring Freedom: Launched in October 2001.
  • Capture of Kabul: Taliban-driven from Kabul by December 2001.
  • NATO Involvement: United Nations authorized NATO-led International Security Assistance Force (ISAF) in 2003.
  • Surge of Troops: President Obama increased US troops in 2009.
  • Osama bin Laden’s Death: Killed in Pakistan in May 2011.
  • Withdrawal: US troops began withdrawing in 2014; complete withdrawal in August 2021.

The Taliban regained control of Afghanistan following the US exit.

Iraq War (2003-2011)

The Iraq War began in 2003 with the invasion of Iraq by a United States-led coalition.

  • Initial Invasion: The operation, termed “Shock and Awe,” aimed to topple Saddam Hussein’s regime.
  • Coalition Forces:
    • United States
    • United Kingdom
    • Australia
    • Poland
  • Key Events:
    • Capture of Baghdad
    • Overthrow of Saddam Hussein
    • Insurgency and sectarian violence
  • Significant Outcomes:
    • Saddam Hussein captured and executed
    • Rise of ISIS
  • Between 2003 and 2011, the conflict saw intense fighting and significant casualties among combatants and civilians.

War in Donbas (2014-2022)

The War in Donbas began in 2014 in Eastern Ukraine. It involved Ukrainian government forces and separatist groups backed by Russia.

Key Events

  1. Annexation of Crimea: Russia’s annexation in March 2014.
  2. Protests: Pro-Russian protests in Donetsk and Luhansk.
  3. Declaration of Independence: Donetsk and Luhansk declared independence in April 2014.
  4. MH17 Incident: Malaysia Airlines Flight MH17 shot down in July 2014.

Humanitarian Impact

  • Thousands of civilians displaced.
  • Numerous casualties on both sides.
  • Destruction of critical infrastructure.

International Response

The international community imposed sanctions on Russia.

The conflict remains unresolved, with ongoing skirmishes and a fragile ceasefire.

Russian Invasion of Ukraine (2022–present)

The conflict began on February 24, 2022, when Russia launched a large-scale military invasion of Ukraine. Major events include:

  • Initial Assault: Russia targeted Kyiv and other major cities.
  • International Response: Widespread condemnation and sanctions by Western countries.
  • Ukrainian Resistance: Strong defense from Ukrainian armed forces and civilian volunteers.
  • Humanitarian Crisis: Millions displaced, extensive civilian casualties.
  • Economic Impact: Global energy prices surged.
  • Diplomatic Efforts: Numerous failed ceasefire attempts and peace talks.
  • Military Aid: Western nations supplied Ukraine with weapons and economic assistance.

Israel–Hamas War (2023–present)

The Israel–Hamas War began in 2023, resulting from escalating tensions. Key events include:

  • October 2023: Hostilities ignite after a series of cross-border attacks.
  • Airstrikes and Rocket Fire: Both sides exchange heavy fire, impacting civilian areas.
  • Ground Invasion: Israeli forces initiate a ground offensive into Gaza.
  • International Reaction: Global powers call for a ceasefire and peace negotiations.
  • Humanitarian Crisis: The conflict leads to significant casualties and displacement.

The war illustrates the ongoing volatility in the region, with deep-seated issues complicating efforts for resolution.