Causes of World War I
World War I resulted from a complex mix of long- and short-term factors that escalated tensions across Europe. These factors are often summarized by the acronym MAINAC:
- M - Militarism: The Industrial Revolution led to an arms race where European nations expanded their military forces in response to each other. As a result, countries built up large armies and stockpiled weapons, which contributed to heightened tensions.
- A - Alliances: Alliances were formed between major European powers, dividing Europe into the Triple Entente (France, Russia, and Great Britain) and the Triple Alliance (Germany, Austria-Hungary, and Italy). These alliances committed countries to support each other in times of war, turning regional conflicts into global ones.
- I - Imperialism: The competition for colonies, especially in Africa and Asia, created rivalries among European powers. The Partition of Africa intensified tensions between European nations as they competed for resources and strategic territories.
- N - Nationalism: Nationalism fueled the desire for countries to assert their power and independence, particularly in regions like the Balkans, where ethnic groups sought to break away from empires (like Austria-Hungary and the Ottoman Empire).
- A - Assassination: The assassination of Archduke Franz Ferdinand of Austria-Hungary by a Serbian nationalist in Sarajevo in June 1914 acted as the immediate spark for the war. Austria-Hungary's response led to a chain reaction of declarations of war.
- C - Crises: Several earlier crises, such as the Moroccan Crises (1905 and 1911) and the Bosnian Crisis (1908), had already strained relations among European powers, particularly between Germany, France, and Austria-Hungary. These crises set the stage for the larger conflict.
The assassination of Franz Ferdinand by the Black Hand, a Serbian nationalist group, triggered a series of events that escalated into a global conflict. Austria-Hungary declared war on Serbia, and due to the web of alliances, Russia, Germany, France, and eventually Great Britain became involved, turning a regional conflict into World War I.
Technological and Military Advancements
World War I marked a major shift in military strategies and technologies, with new innovations that reshaped the nature of warfare.
| Technology | Description |
|---|---|
| Tanks | Tanks were first used in 1916 at the Battle of the Somme. They helped break through trench lines, offering mobility in an otherwise stagnant war. |
| Poison Gas | Chlorine and mustard gas were used to break the stalemate of trench warfare. Poison gas caused widespread injury and death, adding a new level of horror to the war. |
| Submarines (U-boats) | German U-boats targeted merchant and military ships, disrupting supplies to the Allies. The unrestricted submarine warfare policy, which led to the sinking of civilian ships like the Lusitania, was one of the major factors that pushed the United States into the war. |
| Aircraft | Airplanes were used for reconnaissance, bombing, and dogfighting. They played a critical role in gaining air superiority for the Allies in later stages of the war. |
| Machine Guns | Machine guns, such as the Maxim gun, led to devastating casualties on both sides and made traditional military strategies obsolete. |
| Trench Warfare | Trench warfare became the defining feature of the Western Front. Soldiers faced horrific conditions in the trenches, with constant artillery bombardment, disease, and a high death toll from small arms fire and poison gas. |
These technologies led to a stalemate, especially on the Western Front, where both sides struggled to break through entrenched positions. The use of new weapons significantly increased the scale of death and destruction, contributing to the immense casualties of the war.
The Global Impact of World War I
The war in Europe quickly spread to non-European theaters, transforming it into a global conflict.
The Western Front
- The Battle of the Marne (1914) was a pivotal turning point where French and British forces stopped Germany's advance toward Paris. This battle marked the beginning of trench warfare, which would define much of the conflict on the Western Front.
- Trench Warfare dominated the Western Front, creating a deadlock. "No Man's Land" between the opposing trenches became a place of death, with soldiers frequently exposed to machine gun fire, artillery, and poison gas.
The Eastern Front
- On the Eastern Front, fighting between Russia and the Central Powers (Germany and Austria-Hungary) was more fluid than in the West. Despite Russia’s large size, logistical challenges and defeats weakened its military effort.
- The Treaty of Brest-Litovsk (1917) between Soviet Russia and the Central Powers effectively ended Russia's involvement in the war after the Russian Revolution.
The Middle East and Africa
- The Ottoman Empire joined the Central Powers, and the war spread to the Middle East, where the British and French fought against Ottoman forces.
- Africa became a theater of conflict as colonial powers used African soldiers and resources. German colonies were seized by Britain and France.
The United States Joins the War
- The Zimmerman Telegram (1917) revealed Germany's attempt to incite Mexico to attack the United States, which, combined with unrestricted submarine warfare, led the United States to enter the war on the side of the Allies.
- The United States provided critical manpower and resources, tipping the balance of the war in favor of the Allies.
Negotiating Peace
- The Armistice of November 11, 1918, marked the end of fighting, as Germany’s war effort collapsed due to mass casualties, economic hardship, and internal unrest.
- The Treaty of Versailles (1919) officially ended World War I. The treaty imposed heavy penalties on Germany, including territorial losses, military restrictions, and reparations. These harsh terms contributed to the economic and political instability in Germany, eventually leading to World War II.
- The League of Nations was established as part of the treaty, aimed at preventing future conflicts, although it was ultimately ineffective, in part due to the absence of the United States.
Effects of World War I
Political and Diplomatic Effects
- The war led to the collapse of several empires, including the Austro-Hungarian, Ottoman, Russian, and German empires. New countries were created from the remnants of these empires, including Czechoslovakia and Yugoslavia.
- The Russian Revolution of 1917 overthrew the Tsarist regime and led to the rise of the Soviet Union, marking the beginning of communist rule in Russia.
- The war caused a shift in global power, with the United States emerging as a major world power.
Economic Effects
- The war left Europe devastated, both physically and economically. The cost of the war, along with reparations imposed on Germany, led to economic instability in many countries, contributing to the Great Depression in the 1930s.
- The war also led to the disillusionment of many people, who questioned the values and assumptions of previous generations, leading to intellectual and cultural shifts.
Social Effects
- The war caused immense suffering, with millions of casualties, both military and civilian. The widespread use of new weapons, including chemical warfare, left long-lasting physical and psychological scars on those who survived.
- The roles of women in society were significantly altered by the war. With men fighting on the front lines, women entered the workforce in greater numbers, which led to changing social attitudes and increased demands for women's rights.
The Aftermath and Legacy
- World War I's legacy was far-reaching. The harsh terms of the Treaty of Versailles and the economic instability it caused laid the groundwork for the rise of extremist political movements, including fascism and communism, which would lead to World War II.
- The war also set the stage for new forms of diplomacy and international cooperation, with the creation of the League of Nations, despite its ultimate failure in preventing another world war.
World War I was a transformative event in global history, reshaping political, social, and economic structures worldwide, and sowing the seeds for future conflicts.
Vocabulary
The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.
| Term | Definition |
|---|---|
| alliances | Formal agreements between nations to support each other militarily and politically, a key long-term cause of World War I. |
| casualties | Soldiers killed, wounded, or missing in combat; World War I saw unprecedented numbers of casualties due to new military technologies. |
| disillusionment | A widespread loss of faith and confidence in traditional beliefs, values, and institutions following the enormous sacrifices of World War I. |
| imperialism | The policy of extending a country's power and influence through colonization, military force, or other means over foreign territories and peoples. |
| July Crisis of 1914 | The series of diplomatic and military events in July 1914 following the assassination of Archduke Franz Ferdinand that triggered the outbreak of World War I. |
| military technology | Weapons, equipment, and innovations used in warfare, such as machine guns, poison gas, tanks, and aircraft that fundamentally changed combat tactics in World War I. |
| mobilization | The process of organizing and preparing a nation's entire population and economic resources for war. |
| nationalism | A political ideology emphasizing loyalty to one's nation and national interests, which emerged as a reaction to Napoleonic expansion. |
| political participation | The involvement of citizens in the political process and decision-making of their nation. |
| social equality | The principle that all members of society should have equal rights, opportunities, and treatment. |
| total war | A form of warfare in which all of a nation's resources and population are mobilized for the war effort, blurring distinctions between military and civilian targets. |
| trench warfare | A military strategy involving fortified defensive positions with interconnected trenches, used extensively in World War I as a response to new military technologies. |
| women's suffrage | The right of women to vote, which was achieved in Western Europe through feminist efforts and in Eastern Europe and the Soviet Union through government policy. |
Frequently Asked Questions
What were the main causes of World War I?
World War I had both long-term structural causes and a short-term trigger. Long-term: (1) a rigid system of alliances (Triple Entente vs. Triple Alliance) that turned local conflicts into wider ones; (2) rising nationalism that increased tensions in multiethnic empires (especially Austro-Hungarian and Ottoman); (3) imperial rivalry and competition for colonies; and (4) militarism and arms races that made leaders more willing to mobilize. Short-term: the assassination of Archduke Franz Ferdinand in June 1914 set off the July Crisis, when national leaders and military planners made rapid decisions and mobilizations that escalated into general war. The CED keywords to remember: Assassination of Archduke Franz Ferdinand, July Crisis, system of alliances, nationalism, imperialism. For AP prep, you should be ready to explain both the complex long- and short-term causes and link them to effects like total war and trench warfare (Topic 8.2). For a focused review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice 1000+ problems on Fiveable (https://library.fiveable.me/practice/ap-european-history).
Why did World War I actually start and what was the July Crisis?
World War I actually started from a mix of long-term tensions and the short-term July Crisis of 1914. Long-term causes: a tangled system of alliances (Triple Entente vs. Triple Alliance), intense nationalism, imperial rivalry, and military planning that made escalation likely. The short-term trigger was the assassination of Archduke Franz Ferdinand (June 28, 1914) in Sarajevo. The July Crisis was the month-long diplomatic chain reaction: Austria-Hungary’s harsh ultimatum to Serbia, Serbia’s partial acceptance, Austria-Hungary’s mobilization backed by Germany’s “blank check,” Russia’s partial mobilization to protect Slavic Serbia, and Germany’s declarations of war as mobilizations and alliance commitments forced choices. By early August, localized conflict became a general European war. For AP writing, tie short- and long-term causes together (causation) and note effects like trench warfare and total war (CED keywords). Review Topic 8.2 on Fiveable (study guide: https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO; unit: https://library.fiveable.me/ap-european-history/unit-8) and practice questions (https://library.fiveable.me/practice/ap-european-history).
What's the difference between long-term and short-term causes of WWI?
Long-term causes are the deep, structural tensions that built up over decades and made a big European war likely: the system of alliances (Triple Entente vs. Triple Alliance), rival imperialism and competition for colonies, and rising nationalism across empires (Balkan unrest, pan-Slavism). These created a fragile balance and high stakes. Short-term causes are the immediate events and decisions that actually triggered war—most importantly the assassination of Archduke Franz Ferdinand in June 1914 and the diplomatic/military choices during the July Crisis (July 1914), when leaders and commanders rushed mobilizations and gave ultimatums. For the AP exam, you should be able to explain both kinds and connect them (causation skill): show how long-term structures made a regional crisis escalate into total war. For a focused review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO). Want practice applying this on short-answer or LEQ prompts? Try problems at (https://library.fiveable.me/practice/ap-european-history).
How did the alliance system lead to World War I?
The alliance system turned a localized crisis into a Europe-wide war by creating automatic commitments. By 1914 two opposing blocs existed: the Triple Entente (France, Russia, Britain) and the Triple Alliance (Germany, Austria-Hungary, Italy). When Austria-Hungary reacted to the assassination of Archduke Franz Ferdinand, its move against Serbia triggered Russia to mobilize in defense of Slavic allies. Germany’s promise to support Austria-Hungary led it to back aggressive measures; France and Britain were then pulled in by their ties and fear of German strength. That chain-reaction—a short-term July Crisis amplified by long-term alliance obligations—turned a regional crisis into World War I (CED KC-4.1.I, keywords: assassination of Franz Ferdinand, July Crisis, system of alliances). For AP prep, make sure you can “explain the causes” (Unit 8 LO B) and practice causal essays using the World War I study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and 1000+ practice problems (https://library.fiveable.me/practice/ap-european-history).
What new weapons and technology were used in World War I?
World War I introduced technologies that changed how Europeans conducted warfare and tie directly to the CED’s point that new tech produced trench warfare and enormous casualties. Key innovations: rapid-fire machine guns, long-range heavy artillery, and widespread barbed wire made frontal assaults deadly; submarines (U-boats) threatened shipping and brought unrestricted naval warfare; airplanes shifted reconnaissance and later bombing and air combat; tanks (tracked armored vehicles) began to break trench stalemates; poison gas (chlorine, mustard) caused mass suffering and forced protective gas masks; radio/telegraph improved command and coordination; and engineers used improved mines, flamethrowers, and motorized transport to mobilize resources. These advances blurred civilian/military lines and required total-war economies and expanded state power (CED KC-4.1.I.B and KC-4.1.I.C). For review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice 1,000+ AP questions at (https://library.fiveable.me/practice/ap-european-history) to prep for related multiple-choice and FRQ prompts.
Why did World War I turn into trench warfare instead of quick battles?
Because prewar plans assumed fast, decisive moves, militaries expected quick victories. That didn’t happen once war started. New technologies—machine guns, rapid-fire artillery, barbed wire, and accurate rifle fire—made advancing across open ground deadly. Defensive firepower outpaced offensive tactics, so armies dug in to protect themselves: trench warfare. The result was long stalemates with high casualties (KC-4.1.I.B). Attempts to break the deadlock—mass infantry charges, artillery barrages, poison gas, even early tanks and planes—helped only slowly; new tech often favored defense and required new strategies. Strategic aims (alliances, nationalism, imperial rivalry) caused the war, but technology and industrial-scale mobilization turned it into static, attritional warfare (KC-4.1.I.A & C). For AP review, link this to Topic 8.2’s focus on how technology altered conduct of war and to key battles like the Somme and Verdun. For more review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice questions (https://library.fiveable.me/practice/ap-european-history).
How did machine guns and poison gas change how wars were fought?
Machine guns and poison gas changed warfare by making old offensive tactics far more deadly and useless. Rapid-fire machine guns created killing zones that turned open-field charges into slaughter, forcing armies to dig in and rely on trench warfare—a defining feature of World War I that led to stalemate and enormous casualties (see CED: trench warfare, KC-4.1.I.B). Poison gas added a new, terrifying dimension: it could incapacitate or force troops out of trenches, blurred the line between military and civilian suffering, and pushed states toward total war responses (mobilizing industry for gas masks, medical care). Together these technologies shifted strategy from maneuver to attrition, increased casualty rates at battles like the Somme and Verdun, and contributed to wartime disillusionment afterward (KC-4.1.I.E). For more on Topic 8.2, check the Fiveable study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice problems (https://library.fiveable.me/practice/ap-european-history).
What is total war and how was WWI different from earlier wars?
Total war means a conflict that mobilizes whole societies—not just soldiers but economies, governments, and civilians—so the line between front and home front blurs. World War I was different from earlier wars because states drafted millions, converted factories to war production, and used new technologies (machine guns, barbed wire, tanks, poison gas, submarines, airplanes) that made traditional maneuver warfare obsolete and produced trench warfare with huge casualties (e.g., Somme, Verdun). Governments expanded power to ration, censor, and direct labor; civilians became strategic targets (U-boat sinks like the Lusitania mattered diplomatically). WWI was also global in scope, helped collapse empires (Austro-Hungarian, Ottoman, Russian) and led to political upheaval (Russian Revolution) and social change (women’s suffrage, widespread disillusionment). On the AP exam, expect DBQ/LEQ prompts asking you to explain how total war changed state-society relations—use specific examples and CED keywords (total war, trench warfare, Treaty of Versailles). Review Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice questions (https://library.fiveable.me/practice/ap-european-history).
How did World War I affect women and their role in society?
World War I dramatically changed women’s roles. As total war required mass mobilization, millions of women entered factories, transport, clerical jobs, nursing, and agriculture—doing work formerly reserved for men. This shift blurred civilian/military roles and expanded state power (rationing, labor controls), accelerating social and economic change. After the war, those contributions strengthened arguments for political rights: several countries ( Britain 1918 partial, Germany 1918, Austria 1918, and others) expanded suffrage for women. The war also changed cultural expectations—women’s increased visibility and new fashions symbolized wider social change—but progress wasn’t uniform; many women were pushed back into traditional roles during demobilization. These developments tie to CED themes: total war, mobilization of populations, expansion of state power, and new expectations for political participation and social equality (including women’s suffrage). For more review, check the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice questions (https://library.fiveable.me/practice/ap-european-history).
I'm confused about how WWI led to revolutions - can someone explain the connection?
World War I created the conditions for revolutions by massively disrupting societies and political legitimacy. Total war meant whole populations and economies were mobilized, expanding state power and creating shortages, inflation, and huge casualties (trench warfare, new tech). That produced mutinies, strikes, and popular anger; soldiers and civilians who’d sacrificed everything grew disillusioned with old elites and traditional authorities. Empires (Russian, Austro-Hungarian, Ottoman) collapsed or weakened, opening space for revolutionary movements—most dramatically the Russian Revolution of 1917. The war also changed expectations about political participation (women’s suffrage gains) and spread radical ideas. On the AP exam, be ready to connect KC-4.1.I.C–E (total war, social disruption, disillusionment) in SA/LEQ/DBQ responses. For a concise review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and practice questions (https://library.fiveable.me/practice/ap-european-history).
What were the effects of World War I on European society and politics?
World War I reshaped European society and politics in huge ways. It caused enormous casualties and economic disruption, produced trench warfare and mechanized slaughter, and forced total mobilization that expanded state power and blurred civilian/military lines. Politically it toppled empires (Russia, Austro-Hungary, Ottoman, Germany), redrew borders, created the mandate system, and led to the Treaty of Versailles—all of which fueled nationalism and political instability. The war’s social effects included labor unrest, mutinies, revolutions (notably Russia, 1917), wider demands for political participation, and gains in women’s suffrage. Many Europeans became disillusioned with old beliefs and liberal democracy, creating space for radical ideologies and authoritarian leaders in the interwar years. For AP prep, practice framing these as short- and long-term effects (use causation and continuity/change on DBQs/LEQs). For a focused review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and try practice questions (https://library.fiveable.me/practice/ap-european-history).
How do I write a DBQ essay about the causes of World War I?
Start with a clear thesis that answers the prompt about the causes of WWI (e.g., “World War I resulted from a mix of long-term factors—alliances, nationalism, imperialism, arms races—and short-term triggers during the July Crisis of 1914”) and put it in your intro or conclusion. Quickly contextualize (late-19th-/early-20th-century rivalries, colonial competition, and militarization). Use 4+ documents to support distinct parts of your argument—one paragraph for alliances and arms races, one for nationalism/imperialism, one for the July Crisis and leaders’ decisions—and bring in at least one specific piece of outside evidence (e.g., assassination of Archduke Franz Ferdinand, Schlieffen Plan, Moroccan Crises, naval rivalry). For at least two documents, explain POV/purpose/audience (how a government memo differs from a public speech). End by showing complexity: multiple causes interacting and short-term choices turning a regional crisis into total war. For more Topic 8.2 help and sample docs, see the World War I study guide (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO). For unit review and 1,000+ practice questions, check the unit page (https://library.fiveable.me/ap-european-history/unit-8) and practice bank (https://library.fiveable.me/practice/ap-european-history).
What happened to the Ottoman and Austro-Hungarian empires after WWI?
After WWI both the Ottoman and Austro-Hungarian empires collapsed, reshaping Europe and the Middle East. The Austro-Hungarian Empire dissolved (1918), splitting into new nation-states—Austria, Hungary, Czechoslovakia, and parts went to Romania, Poland, and Yugoslavia—driven by nationalist movements and military defeat. The Ottoman Empire lost most of its Arab provinces and was partitioned by the Allies; the Turkish War of Independence led by Mustafa Kemal Atatürk produced the Republic of Turkey (1923) and the end of the Ottoman sultanate. Former Ottoman territories were administered under the League of Nations mandate system (e.g., British mandates in Iraq and Palestine; French in Syria and Lebanon). These outcomes connect to CED themes: collapse of empires, mandate system, and creation of modern Turkey—high-value stuff for AP essays and short answers (see Topic 8.2 study guide: https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO). For more review and practice, check the Unit 8 overview (https://library.fiveable.me/ap-european-history/unit-8) and practice questions (https://library.fiveable.me/practice/ap-european-history).
Why did so many people become disillusioned after World War I ended?
So many people were disillusioned after World War I because the war shattered old assumptions and caused massive human, social, and political disruption. New technologies (machine guns, poison gas, tanks, U-boats) produced trench warfare and ≈10 million military deaths and millions more wounded—making victory feel hollow (CED: trench warfare; new tech). Total war blurred civilian/military lines, expanded state power, and upended economies and daily life (CED: total war). The collapse of empires (Austro-Hungarian, Ottoman, Russian) and the punitive Treaty of Versailles left unresolved grievances and national humiliation. Intellectuals and artists questioned traditional beliefs and authority; widespread mutinies, revolutions (e.g., Russia), and political radicalism showed loss of faith in prewar institutions (CED: discontent and revolution). These themes show up often on AP prompts (SAQ/DBQ/LEQ) about causes, effects, and cultural responses—review Topic 8.2 on Fiveable for summaries (https://library.fiveable.me/ap-european-history/unit-8/world-war-1/study-guide/oVbBctdhCZgYi3ZADgtO) and try practice questions (https://library.fiveable.me/practice/ap-european-history).