World War I: Causes, Course and Lasting Consequences

Posted on Jan 25, 2026 in History

Causes of World War I

Long-term causes

  • Militarism: Long-term build-up of armies and an arms race prepared nations for war.
  • Alliances: Otto von Bismarck (19th century) helped shape alliance systems.
    • Triple Entente: France, Russia, Great Britain
    • Triple Alliance: Germany, Italy, Austro-Hungarian Empire
  • Imperialism: Competition for territories and new markets.
  • Nationalism: Many nations and ethnic groups sought independence.
  • Psychological causes: Governments idealized the war and promoted sentiments like love of country, loyalty and bravery.
  • Casus belli: Assassination of Archduke Franz Ferdinand.

Europe: political and economic power

  • Political: Large empires (Great Britain, France, Holland).
  • Economic: Europe produced 43% of the world’s industrial output. Germany: 16% (Thyssen). USA: 26% production. Asia: 20% production.

1914–1918: Course of the War

1914

  • Two fronts (both were very balanced; they would not be home by Christmas).
  • Western Front: Schlieffen Plan — Germany attempted to defeat France by invading Belgium (attack on France via Belgium).
  • Eastern Front: Russia and Germany/Austria-Hungary clashed; Battle of Tannenberg.

1915–1916

  • War in the trenches: long, terrible stalemate; new territories became involved.
  • Long and terrible but did not solve the underlying problems.
  • Everyone wanted to control enemy resources.
  • Germany used submarines to attack commercial ships.
  • 1916: Battle of Jutland — naval battle in the North Sea.
  • Two fronts: Western (Verdun, Somme) and Eastern (German advances).
  • New southern front: Italy joined the Allies; Bulgaria joined the Central Powers.

1917

  • Submarine attacks intensified, aiming to blockade the Allies.
  • United States: Entered the war following incidents such as the Zimmerman telegram to Mexico.
  • Russia: Stopped fighting and signed the Treaty of Brest-Litovsk (Germany and Russia) during the Russian Revolution.
  • The public was very tired of the war; destruction occurred all over Europe.

1918

  • Germany launched a fast offensive.
  • The Western Front was still active; Germany prepared to attack again.
  • Turkey, Austria-Hungary, and Bulgaria were collapsing; Germany found itself largely alone. The Weimar Republic was established in Germany.

Consequences

1. Demographic

  • Approximately 10 million deaths (mostly young men); about 7.5 million deaths in Europe.
  • Birth rates decreased during the war years.
  • Spanish influenza (1917–18 in this text) further affected populations; populations aged.
  • Consequences in population: a “lost generation”; populations became more feminized, which changed social structure.

2. Social and economic

  • After the war, European countries (GB, FR, Germany) were ruined by huge war costs.
  • To solve things, European countries asked for loans, especially from the USA.
  • This created inflation because they printed too much money.
  • USA: Became the leading world power because it suffered no direct material losses, had huge gold reserves, and European countries had borrowed large sums.

3. Ideological consequences

  • During the war, those who opposed the conflict were censored, imprisoned, or forced into exile.
  • Some socialists criticized the war, while others supported it out of patriotism.
  • Pessimism became the general mood. Governments used propaganda against the enemy.

4. Territorial consequences

  • The Austro-Hungarian Empire disappeared and new states appeared: Czechoslovakia, Hungary, Austria. Romania became larger.

The Treaty of Versailles (1919)

It was the peace treaty signed by Germany and the other European countries after World War I. The Treaty of Versailles was seen by Germany as a humiliating agreement; this perception later contributed to the rise of Nazism and to the outbreak of World War II.

  • The German Empire lost the region of Alsace-Lorraine to France (disputed since 1871).
  • Great Britain, France and Italy were members of the Triple Entente. (Triple Entente: France, Russia, GB)
  • Bosnia-Herzegovina was controlled by the Austro-Hungarian Empire after 1878. (True)
  • North Africa was an area where European countries competed for control of colonies. (True)
  • Switzerland was not a member of the Triple Alliance. (False — neutral)
  • GB and Germany competed in a naval arms race prior to the First World War. (True)
  • Franz Ferdinand was heir to the Austro-Hungarian throne, not the German Empire. (False)
  • Abbreviations: T.A. = German Empire, Italy, Austro-Hungary. T.E. = France, GB, Russia. Neither = Spain, Denmark, (Ottonmark is unclear in original).

Miscellaneous statements

The following statements appear in the original notes; they are listed here without removal or cutting (numbers remain as in the source):

  • The Allies made advances in the east and the west. 3
  • The US joined the Allies. 2
  • The armistice was signed. 3
  • Germany invaded Belgium and France. 1
  • The Germans tried to stop Russian advances. 1
  • The German emperor abdicated. 3
  • Soldiers used trenches to defend their positions.

Countries and alliances

  • Countries that belonged to the Triple Alliance and later became the Central Powers: Germany, Austro-Hungarian Empire.
  • Countries that belonged to the Triple Entente and later became the Allied Powers: United Kingdom, France, Russia.
  • Countries that joined the Central Powers: Bulgaria, Ottoman Empire.
  • Countries that joined the Allied Powers: USA, Japan, Portugal, Italy, Serbia, Romania, Greece.

Short questions and answers

  • What was Spain’s position during the First World War? Neutral
  • When and why did Italy join the Allied Powers? 1915, because Italy hoped to gain territory from Austro-Hungary.
  • Which countries were involved in the dispute that started the war? Germany, Austro-Hungary, Serbia.
  • Which side won the war? The Allies

Addresses and Correspondence

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Useful Connectors and Translations

Furthermore = además. Whereas = mientras que. For instance = por ejemplo. As well as = además de. Nevertheless = sin embargo. Therefore = por lo tanto. In order to = con el objetivo de. Due to = debido a. In spite of = a pesar de.