Causes and Effects of Wars

This document covers the IB History topic on the Causes and Effects of (20th Century) Wars for Paper 2. It examines the two World Wars in depth, comparing their origins, courses, and consequences, and explores the major historiographical debates. The focus is on developing the analytical skills needed for high-scoring essay responses.

1. World War I (1914—1918)

1.1 Long-Term Causes

Alliances

• The alliance system created a rigid structure in which a local conflict could rapidly escalate into a general European war
• Triple Alliance (1882): Germany, Austria-Hungary, Italy
• Triple Entente (1907): France, Russia, Britain
• Alliances were intended to deter war by creating a balance of power, but in practice they created a situation in which any conflict between two powers would draw in their allies
• Italy switched sides in 1915, joining the Entente
• The alliances were not automatic — all governments chose to mobilise — but the system created tremendous pressure to act

Militarism

• The arms race between the major European powers created an atmosphere of tension and suspicion
• Anglo-German naval rivalry: Germany”s decision to build a large fleet (Risk Theory) provoked a British response — the naval arms race was a significant factor in worsening Anglo-German relations
• Conscription and large standing armies created the capacity for rapid mobilisation, which meant that any crisis could escalate very quickly
• Military planning (e.g., the Schlieffen Plan) locked powers into rigid offensive strategies
• War was increasingly seen as a legitimate tool of statecraft — social Darwinist ideas glorified military conflict

Imperialism

• Imperial rivalries created friction between the major powers, particularly in Africa, Asia, and the Middle East
• The Moroccan Crises (1905 and 1911) heightened tensions between Germany and France/Britain
• The Boer War (1899—1902) damaged Britain’s reputation and emboldened Germany
• Imperial competition was both a cause of tension and a motive for war — control of colonies meant access to raw materials, markets, and strategic positions

Nationalism

• Nationalism was perhaps the most powerful long-term cause of WWI
• Pan-Slavism: Russia saw itself as the protector of the Slavic peoples; Serbia’s nationalist ambitions threatened Austria-Hungary
• German nationalism: the desire for “a place in the sun” (Weltpolitik) — a global role commensurate with Germany’s growing economic and military power
• French nationalism: the desire to regain Alsace-Lorraine, lost to Germany in 1871, and to avenge the humiliation of defeat
• Nationalism in the Balkans was particularly destabilising: the First and Second Balkan Wars (1912—1913) demonstrated the region’s volatility

1.2 Short-Term Triggers

The July Crisis (1914)

• Archduke Franz Ferdinand of Austria-Hungary was assassinated in Sarajevo on 28 June 1914 by Gavrilo Princip, a Bosnian Serb nationalist with links to the Serbian secret society, the Black Hand
• Austria-Hungary issued an ultimatum to Serbia on 23 July — deliberately designed to be unacceptable
• Serbia accepted most but not all terms; Austria-Hungary declared war on 28 July
• Russia mobilised in support of Serbia
• Germany mobilised in support of Austria-Hungary and declared war on Russia (1 August) and France (3 August)
• Germany invaded Belgium on 4 August — Britain declared war the same day, citing the Treaty of London (1839) guaranteeing Belgian neutrality

The Question of Responsibility

• All the major powers share some responsibility — the July Crisis was a collective failure of diplomacy
• Austria-Hungary was reckless in issuing an ultimatum it knew Serbia could not fully accept
• Germany gave Austria-Hungary a “blank cheque” and implemented the Schlieffen Plan
• Russia’s mobilisation was the trigger for German action, but it was a response to Austrian aggression
• France and Britain became involved because of their alliance commitments
• The “slide into war” was not inevitable — decisions were made by individuals with alternatives

1.3 Course of the War

• Initial German advance through Belgium and into France was halted at the Battle of the Marne (September 1914)
• Both sides dug in — the Western Front became characterised by trench warfare
• Key battles on the Western Front: Verdun (1916), the Somme (1916), Passchendaele (1917)
• The Eastern Front was more fluid: Russia’s initial advance into East Prussia was defeated at Tannenberg (1914); Russia eventually collapsed into revolution (1917)
• New weapons: machine guns, poison gas, tanks, aircraft, submarines
• The war of attrition: by 1917, all combatants were exhausted
• US entry (April 1917) — prompted by unrestricted submarine warfare and the Zimmermann Telegram — tipped the balance
• The German Spring Offensive (1918) nearly succeeded but ultimately failed
• Germany sued for armistice on 11 November 1918

1.4 Treaty of Versailles and Consequences

Key Terms

• Article 231: the “war guilt clause” — Germany accepted sole responsibility for starting the war
• Reparations: initially set at 132 billion gold marks (£6.6 billion) — an enormous sum
• Territorial losses: Alsace-Lorraine returned to France; Eupen-Malmedy to Belgium; West Prussia and Posen to Poland (creating the Polish Corridor); all colonies lost
• Military restrictions: army limited to 100,000; no conscription; no air force; limited navy; Rhineland demilitarised
• League of Nations established as an international body for collective security

Consequences

• The treaty was widely resented in Germany — the “stab-in-the-back” myth blamed defeat on domestic betrayal rather than military defeat
• France wanted a harsher treaty; Britain wanted a more moderate approach; the USA wanted a “peace without victory” (Wilson’s Fourteen Points)
• The treaty created as many problems as it solved: the reparations issue poisoned international relations; territorial changes created new minorities; the League of Nations lacked enforcement power
• The treaties with Austria, Hungary, Bulgaria, and Turkey (St. Germain, Trianon, Neuilly, Sevres/Lausanne) dismantled the Austro-Hungarian and Ottoman empires

2. World War II (1939—1945)

2.1 Causes

Failures of the Treaty of Versailles

• The treaty’s harshness created lasting resentment in Germany
• Reparations and economic hardship contributed to political extremism
• The treaty did not create a stable European order — it merely created a “twenty-year armistice” (Foch)
• The USA never ratified the treaty or joined the League of Nations, undermining the settlement
• The failure to enforce the treaty’s provisions (e.g., German rearmament) eroded its credibility

Appeasement

• The policy of appeasement — making concessions to avoid conflict — was the dominant Western approach to Nazi Germany in the 1930s
• Key examples: German remilitarisation of the Rhineland (1936) — no response; Anschluss with Austria (1938) — accepted; the Sudetenland (Munich Agreement, September 1938) — Britain and France sacrificed Czechoslovakia
• Reasons for appeasement: memory of WWI horrors, pacifist public opinion, anti-communism (some saw Hitler as a bulwark against Stalin), British rearmament was incomplete, genuine belief that Hitler’s demands were limited
• Munich was initially seen as a triumph (“peace for our time” — Chamberlain); it became a byword for cowardice when Hitler invaded the rest of Czechoslovakia in March 1939
• When Germany invaded Poland (1 September 1939), Britain and France declared war — appeasement was finally abandoned

Nazi Expansionism

• Hitler’s ideology demanded Lebensraum (living space) in Eastern Europe
• His foreign policy was deliberately provocative and designed to test Western resolve
• Rearmament in defiance of Versailles (from 1935)
• Remilitarisation of the Rhineland (1936)
• Anschluss with Austria (March 1938)
• Annexation of the Sudetenland and then all of Czechoslovakia (1938—1939)
• Nazi-Soviet Pact (August 1939): non-aggression pact with secret protocol to partition Poland
• Invasion of Poland (1 September 1939)

Other Factors

• The Great Depression destabilised democracies and enabled the rise of fascism
• The League of Nations failed to prevent aggression — the Manchurian Crisis (1931), the Abyssinian Crisis (1935), and German rearmament all went unpunished
• The USA’s isolationism reduced the capacity for collective action
• The USSR’s signing of the Nazi-Soviet Pact allowed Hitler to avoid a two-front war in 1939

2.2 Key Events

• Blitzkrieg in Poland (September 1939): Germany’s combined arms tactics led to rapid victory
• Fall of France (May—June 1940): the Low Countries and France fell in six weeks; the BEF was evacuated from Dunkirk
• Battle of Britain (July—October 1940): the Luftwaffe failed to achieve air superiority; Britain survived
• Operation Barbarossa (June 1941): Germany invaded the USSR with 3 million troops; initial successes gave way to catastrophe
• Pearl Harbor (7 December 1941): Japan attacked the US Pacific Fleet; the USA entered the war
• Battle of Midway (June 1942): turning point in the Pacific war
• Battle of Stalingrad (August 1942 — February 1943): German 6th Army destroyed; the war’s turning point in Europe
• D-Day (6 June 1944): Allied invasion of Normandy opened the Western Front
• Fall of Berlin (April—May 1945): Hitler committed suicide; Germany surrendered 8 May 1945
• Atomic bombs (August 1945): Hiroshima (6 August) and Nagasaki (9 August); Japan surrendered 15 August 1945

2.3 Consequences

The Cold War

• The wartime alliance between the USA and USSR quickly dissolved
• Europe was divided into Western and Soviet spheres of influence
• The Iron Curtain descended across the continent
• The Cold War defined international relations for the next 45 years

Decolonisation

• European colonial empires were weakened by the war
• Britain, France, and the Netherlands could no longer maintain their empires
• India gained independence in 1947; the process of decolonisation accelerated across Africa and Asia
• The war exposed the contradictions of colonial rule — colonial troops had fought for freedom in Europe

The United Nations

• The UN was established in 1945 to prevent future wars
• The Security Council (with five permanent members and veto power) reflected the new power structure
• The Universal Declaration of Human Rights (1948) established international human rights standards

The Holocaust

• The systematic murder of 6 million Jews and millions of others by the Nazi regime
• Led to the Nuremberg Trials (1945—1946) — establishing the principle of individual criminal responsibility for crimes against humanity
• Created the legal and moral framework for international human rights law

Europe’s Reconstruction

• The Marshall Plan (1948—1952) funded Western European recovery
• Eastern Europe came under Soviet control
• Germany was divided and became the central flashpoint of the Cold War

3. Comparison: WWI vs WWII

3.1 Causes Compared

3.2 Treaty Comparisons

• Versailles (1919) vs the post-WWII settlements: the post-1945 settlements were arguably more successful because they involved the defeated powers in reconstruction (Marshall Plan, NATO) rather than punishing them
• The lesson learned: the harshness of Versailles contributed to WWII; the generosity of the post-1945 settlement contributed to a stable peace in Western Europe

3.3 Lessons Learned

• The League of Nations failed because it lacked enforcement power and the USA was not a member
• The UN was designed to address these weaknesses, but the Security Council veto limited its effectiveness during the Cold War
• Appeasement was discredited after WWII, but the concept of collective security through NATO proved more effective

4. Historiographical Debates

4.1 The Fischer Thesis

• Fritz Fischer’s Germany’s Aims in the First World War (1961) argued that Germany bore primary responsibility for WWI
• Fischer argued that Germany had deliberate expansionist war aims (September Programme, 1914) and that the war was not an accident but the result of deliberate German policy
• This challenged the prevailing German view that Germany was a victim of encirclement
• Fischer’s work was controversial in Germany but is now widely accepted in modified form

4.2 Collective Guilt vs Shared Responsibility

• Article 231 of Versailles imposed sole war guilt on Germany — this is now widely seen as unfair and counterproductive
• Modern historians generally agree that responsibility was shared among all the major powers
• The July Crisis was a collective failure of diplomacy in which all parties made bad decisions
• The debate has shifted from “who was responsible?” to “why did the system fail?“

4.3 Revisionist Views

• Some revisionist historians argue that WWI was not inevitable — it was the result of specific decisions that could have gone differently
• Others emphasise structural factors (alliances, militarism, imperialism) that made war highly probable even if not strictly inevitable
• The debate between intentionalist and structuralist explanations mirrors similar debates about WWII and the Cold War

5. Essay Writing for Cause/Effect Questions

1. Distinguish between causes, triggers, and preconditions: Long-term causes create conditions; short-term triggers set events in motion. Both must be addressed.
2. Use the STEEP framework: Structure your analysis around Social, Technological, Economic, Environmental, and Political factors. This ensures breadth.
3. Assess relative significance: Not all causes are equally important. Justify your judgement about which factors were most significant and why.
4. Avoid chronological narrative: Structure by theme or argument, not by date. Use chronological order only within individual paragraphs.
5. Link causes and effects: Show how specific wartime decisions led to specific post-war outcomes. The Versailles Treaty’s consequences for WWII is a classic linkage.
6. Use counterarguments: Acknowledge alternative interpretations and explain why your argument is stronger. This demonstrates critical thinking.
7. Provide specific evidence: Names, dates, statistics, and treaty provisions carry more weight than general statements.

6. Common Pitfalls

1. Narrative over analysis: Telling the story of a war is not the same as analysing its causes or effects. Always maintain an argumentative focus.
2. Mono-causal explanations: Wars have complex, multi-causal origins. Reducing them to a single cause (e.g., “WWI was caused by the alliance system”) is inadequate.
3. Presentism: Judging historical actors by contemporary standards. The decisions made in 1914 must be understood in the context of the time.
4. Confusing correlation with causation: Just because two events occurred together does not mean one caused the other. Evidence of causal linkage is required.
5. Neglecting the effects: Many essays focus heavily on causes at the expense of effects. Both must be addressed in a balanced way.
6. Over-generalisation: Statements like “the Treaty of Versailles caused WWII” are too simplistic. Specify which aspects of the treaty contributed and through what mechanisms.
7. Ignoring multiple perspectives: The causes of war look different from Berlin, London, Moscow, and Vienna. Acknowledging different national perspectives strengthens analysis.

7. Summary

The two World Wars were the defining catastrophes of the 20th century, and understanding their causes and consequences is central to the study of modern history. WWI resulted from the interplay of alliances, militarism, imperialism, and nationalism, triggered by a crisis in the Balkans. WWII emerged from the failures of the Versailles settlement, the policy of appeasement, and Nazi expansionism. Both wars had profound and lasting consequences — the redrawing of borders, the collapse of empires, the creation of new international institutions, and the onset of the Cold War. The historiographical debates surrounding these wars remain vibrant and essential to the development of sophisticated historical analysis.

Worked Examples

Worked examples demonstrating the application of key concepts are covered in the detailed sub-pages linked above.