AG

Causes and Effects of 20th-Century Wars

Causes of 20th-Century Wars

Political

Imperialism

  • The strategy of extending power

  • Competition over colonies and resources

  • Had an impact on relations in Europe and caused global tension

  • Ex. the Scramble for Africa 

Militarism

  • Military planning

  • Nations rushing to get more and more weapons

  • Military leaders influenced politics

  • Ex. the Arms Race 

Alliances

  • Forming alliances and their impacts (Ex. Triple Entente, Triple Alliance, etc.)

  • Balance of power and entangling alliances

Revolutions and Civil Wars

  • Russian Revolution and Civil War

  • Chinese Civil War

Great Depression (1929)

  • Global economic impact

  • Rise of extremist movements (Nazism, Fascism, etc.)

Colonial Independence Movements

  • Decolonization in Africa and Asia

  • European withdrawals impact

Territorial

Border Disputes

  • India and Pakistan

  • Arab and Israeli 

  • Germany and Poland

Ideological Conflicts

  • Democracy v. Totalitarianism 

  • Capitalism v. Communism

Class Struggles

  • Labor movements and social unrest

  • Marxism and socialism influence

Nationalism

  • Support of one’s nation to the extreme of putting down other nations

  • Ex. German nationalism during WWII

Foreign Influence

  • Japan’s influence in Asia

  • Germany’s influence in Europe

Economic

Resource Competition

  • Oil, rubber, weapons, and strategic materials

  • Economic sanctions

  • Trade embargoes

Types of Wars and Technological Developments

Types of Wars

Civil War

  • A war between groups or factions within the same country or state.

  • Often arises due to political, social, or economic disagreements.

  • Can involve both regular military forces and irregular fighters.

War Between States

  • A conflict between two or more separate, independent nations or states.

  • May be triggered by territorial disputes, resource competition, or ideological differences.

  • Generally involves organized military forces, with defined borders and formal declarations of war.

Guerrilla Warfare

  • A form of irregular warfare where small, mobile groups of fighters (guerrillas) use tactics like ambushes, sabotage, and hit-and-run attacks.

  • Typically employed by weaker forces against a stronger, conventional military.

  • Fighters rely on knowledge of the local terrain, surprise, and avoiding direct confrontations with a larger enemy.

  • Often used in resistance movements or insurgencies.

Technological Developments

Air Warfare

  • The use of aircraft, such as planes and drones, to engage in combat.

  • Involves tactics like bombing, airstrikes, and aerial dogfights.

  • Primarily focused on controlling airspace and gaining superiority over the enemy’s aerial forces.

  • Often used for reconnaissance, intelligence gathering, and precision strikes.


Naval Warfare

  • The use of ships, submarines, and other watercraft to fight on or under the sea.

  • Includes tactics like naval blockades, surface combat, submarine warfare, and amphibious assaults.

  • Aims to control vital sea routes, project power, and defend or disrupt maritime trade.

  • Can involve large-scale fleet engagements or small, tactical skirmishes.

Land Warfare

  • Combat is fought on the ground, typically between armies and other ground-based forces.

  • Involves infantry, tanks, artillery, and other land-based military assets.

  • Focused on occupying and controlling territory, fortifications, and key infrastructure.

  • Often involves large-scale battles, sieges, and various tactics like flanking, trench warfare, or urban combat.

Effects of 20th-century Wars

Political Effects

Redrawing of Borders

  • Treaty of Versailles and its impact on Europe; imposing harsh penalties on Germany, including territorial losses, heavy war reparations, and acceptance of blame for the war, which ultimately led to widespread resentment and contributed to the rise of Adolf Hitler and the seeds of World War II

  • Post-World War II borders and the division of Germany

Rise of Totalitarian Regimes

  • Nazi Germany

  • Fascist Italy

  • Soviet Union

Creation of International Organizations

  • League of Nations; overall impact on Europe was largely considered a failure due to its inability to stop major aggression from powerful nations like Germany, Italy, and Japan

  • United Nations; a platform for addressing issues like human rights, migration, sustainable development, and peacebuilding

Cold War Dynamics

  • USA v. USSR

  • Formation of NATO and Warsaw Pact; never directly waged war against each other in Europe

Economic Effects

Destruction and Reconstruction

  • Post-war reconstruction efforts (Marshall Plan); provided much-needed capital and materials that enabled Europeans to rebuild the continent's economy

  • Economic boom and industrial growth

Shifts in Global Economic Power

  • Decline of European colonial powers

  • Rise of the United States and the Soviet Union

War Economy and Technological Advancements

  • Military-industrial complex

  • Innovations in technology and industry

Social Effects

Human Cost

  • Casualties, displacement, and refugee crises

  • Psychological impact and trauma

Social Changes

  • Women’s role during and after wars

  • Civil rights movements and social reforms

Cultural Impacts

  • Changes in art, literature, and philosophy

  • Collective memory and commemoration of wars

Environmental Effects

Destruction of Landscapes

  • Impact of battles on cities and countryside

Long-Term Environmental Damage

  • Nuclear testing and radiation

  • Use of chemical weapons (Agent Orange in Vietnam)

Key Wars

World War I (1914-1918)

  • Caused by Assasination of Archduke Franz Ferdinand, nationalism, militarism, and alliances

  • Major Battles: Battle of the Somme, Battle of Verdun

  • Effects: Treaty of Versailles, League of Nations, redrawn European borders

World War II (1939-1945)

  • Caused by Treaty of Versailles, expansionist policies of Axis powers, failure of appeasement

  • Major Battles: Battle of Stalingrad, D-Day (Normandy Invasion)

  • Effects: United Nations, Cold War onset, decolonization

Korean War (1950- 1953)

  • Caused by division of Korea, rise of Communism, Cold War dynamics

  • Major Battles: Battle of Inchon, Battle of Pusan Perimeter

  • Effects: Korean Armistice Agreement, ongoing North-South Korean tensions

Vietnam War (1955- 1975)

  • Caused by French colonialism, rise of Communism, Cold War dynamics

  • Major Battles: Tet Offensive, Battle of Dien Bien Phu

  • Effects: Reunification of Vietnam, significant US military and social impact

Cold War (1947- 1991)

  • Caused by ideological conflicts between US and USSR, nuclear arms race

  • Major Incidents: Cuban Missile Crisis, Berlin Blockade

  • Effects: Fall of the Soviet Union, end of bipolar world order

Arab- Israeli Conflicts (1948- present)

  • Caused by creation of Israel, territorial disputes, nationalism

  • Major Wars: Six-Day War, Yom Kippur War

  • Effects: Formation of new nations, legacy of colonial borders and conflicts

Key Figures

World War I

Archduke Franz Ferdinand (Austria- Hungary)

  • Heir to the Austro-Hungarian throne

  • His assassination in Sarajevo triggered WWI

Kaiser Wilhelm II (Germany)

  • Emperor of Germany

  • Enforced aggressive foreign policy and militarism

Woodrow Wilson (United States)

  • 28th President of the United States

  • Proposed the Fourteen Points and League of Nations

Georges Clemenceau (France)

  • Prime Minister of France

  • Strong advocate for punishing Germany in Treaty of Versailles

David Lloyd George (United Kingdom)

  • Prime Minister of the United Kingdom

  • Played a key role in the peace negotiations at Versailles

World War II

Adolf Hitler (Germany)

  • Leader of the Nazi Party

  • Initiated WWII with expansionist policies

Franklin D. Roosevelt (United States)

  • 32nd President of the United States

  • Led the US through the Great Depression and WWII

Winston Churchill (United Kingdom)

  • Prime Minister of the United Kingdom

  • Famous for his leadership and speeches during the war

Joseph Stalin (Soviet Union)

  • Leader of the Soviet Union

  • Key figure in the Allied victory and post-war Soviet expansion

Benito Mussolini (Italy)

  • Fascist leader of Italy

  • Allied with Nazi Germany

Hirohito (Japan)

  • Emperor of Japan

  • Oversaw Japan’s military expansion and eventual surrender

Cold War

Harry S. Truman (United States)

  • 33rd President of the United States

  • Implemented the Truman Doctrine and Marshall Plan

Nikita Khrushchev (Soviet Union)

  • Leader of the Soviet Union

  • Known for de-Stalinization and the Cuban Missile Crisis

John F. Kennedy (United States)

  • 35th President of the United States

  • Faced the Cuban Missile Crisis and promoted the space race

Ronald Reagan (United States)

  • 40th President of the United States

  • Played a key role in ending the Cold War with his aggressive stance against the USSR

Mikhail Gorbachev (Soviet Union)

  • Last leader of the Soviet Union

  • Implemented reforms like Perestroika and Glasnost

Other Wars

Kim Il-sung (North Korea) - Korean War

  • Founder and first leader of North Korea

  • Initiated the Korean War by invading South Korea

Ho Chi Minh (Vietnam) - Vietnam War

  • Leader of the Vietnamese independence movement

  • Key figure in the fight against French and American forces

Gamal Abdel Nasser (Egypt) - Arab- Israeli Conflicts

  • President of Egypt

  • Led Egypt during the Suez Crisis and Six-Day War

Jawaharlal Nehru (India) - India- Pakistan Conflicts

  • First Prime Minister of India

  • Played a central role in India’s independence and early conflicts with Pakistan