Origins and Outbreak of World War I

Posted on Jan 12, 2026 in History

Causes of World War I

I. Intense Global Rivalry

The distribution of global power led to tremendous rivalry between major powers. These confrontations were intensified by the complex system of alliances and enmities established in Europe between 1870 and 1890.

II. The Armed Peace (1890–1914)

From 1890, the German Empire, led by Kaiser William II, launched an aggressive expansionist policy. William initiated a significant program of investment in arms and naval fleets and actively intervened in overseas conflicts. The attitude of the Germans aroused deep suspicions among other European states, prompting them to begin parallel policies of rearmament.

Furthermore, two new rivals emerged with significant interests in the Pacific: the USA and Japan.

Between 1890 and 1914, a period known as the armed peace unfolded, characterized by the following diplomatic maneuvers:

  • France: Broke its isolation by forming an alliance with Russia. It improved its relationship with Great Britain (GB) and relied on the conflict in Morocco. By 1904, France and GB had consolidated the Entente Cordiale.
  • Russia: Allied with France, it later solidified its friendship with GB. Subsequently, Russia reached an agreement with GB in 1907 to divide spheres of influence in Central Asia.
  • Great Britain (GB): Decided to break its traditional isolation and became part of a triple understanding with France and Russia.
  • Austria-Hungary: Retained the Triple Alliance (with Germany and Italy).
  • Italy: Shifted towards France and the UK, becoming an unreliable partner for the Central Powers.
  • Japan and USA: The U.S. gained possessions in the Pacific. Japan expanded throughout the Pacific, achieving hegemony over the Korean peninsula and Manchuria.

III. The Crisis in the Balkans

International relations were severely tested by a new episode of the long-standing conflict in the Balkans. Incidents began in 1908 when Austria-Hungary annexed Bosnia-Herzegovina.

The expansionist ambitions of states emerging from the decaying Turkish Empire led to the next crisis in 1912:

First Balkan War (1912–1913)

Greece, Montenegro, Bulgaria, and Serbia formed an alliance and declared war on the Turkish Empire, ultimately defeating it.

Second Balkan War (1913)

The victorious Balkan countries immediately began fighting amongst themselves. This time, Bulgaria faced Serbia, Greece, and Turkey, with Romania joining the latter two. The main winner was Serbia, which expanded its territory in Macedonia. Additionally, a new independent state, Albania, was created.

The Balkan crisis did not end in 1913. The following year, a conflict erupted in the area that would trigger the First World War.

IV. Outbreak of the First World War (1914–1918)

The term First World War (1st G. Mundial) designates the conflict that occurred between 1914 and 1918. It was the only truly massive European war.

The war erupted in Europe, involving the primary European powers. As most of these nations possessed colonies worldwide, the intervention of Japan and the U.S. transformed what began as a European war into a global conflict.

The Spark in Sarajevo

The war started in the Balkans. On June 28, 1914, the heir to the Austro-Hungarian throne and his wife were assassinated while visiting Sarajevo, a Bosnian town. The perpetrators had prepared this operation in Belgrade.

The attack provided Austria-Hungary with the perfect excuse to present Serbia with a set of severe conditions. When the Serbs refused to accept all demands, Austria-Hungary declared war on July 28.

The Chain Reaction of Alliances

Following Austria’s declaration of war, the other powers joined the fray in compliance with their existing alliances and agreements:

  1. Russia mobilized its troops to intervene if necessary.
  2. Germany, Austria-Hungary’s ally, demanded Russia cease these operations and called for France to remain neutral.
  3. Upon receiving no satisfactory response, on August 1, Germany declared war on Russia, and on August 3, declared war on France.
  4. To execute its military plan, the Germans invaded neutral Belgium, which immediately caused Great Britain to enter the war (August 4).
  5. Later, other countries joined: Bulgaria and the Turkish Empire joined the Central Powers. Romania and Greece joined the allies of Russia and France.
  6. Italy initially did not support its allies but entered the war on the side of the Entente in 1915.
  7. The U.S. joined the conflict in 1917.
  8. Spain remained neutral throughout the entire conflict.