1. Assassination of Archduke Franz Ferdinand: On June 28, 1914, Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, was assassinated in Sarajevo by a Serbian nationalist named Gavrilo Princip. This act sparked outrage and tension between Austria-Hungary and Serbia.
2. Diplomatic Crisis and Ultimatum: Austria-Hungary issued an ultimatum to Serbia, demanding an apology and punishment for those involved in the assassination. Serbia agreed to most of the demands but rejected some, leading to a breakdown in diplomatic negotiations.
3. Russian Mobilization: Russia, as Serbia's ally, began mobilizing its military in support of Serbia. This was seen as a direct threat by Germany, which viewed Russia's actions as a preparation for war.
4. German Declaration of War: On August 1, 1914, Germany declared war on Russia and France, fearing a two-front war if Russia was allowed to mobilize fully. Germany's actions officially triggered the outbreak of World War I.
Underlying Factors and Long-Term Causes:
1. Nationalism and Imperialism: European nations were competing for colonies, resources, and influence around the world. Nationalistic sentiments and imperial rivalries created tensions and animosities between countries.
2. Militarism: Many European countries had built up large and powerful military forces in the years leading up to the war. This arms race and the glorification of military power contributed to the atmosphere of tension and preparedness for conflict.
3. System of Alliances: A complex web of alliances between European countries meant that a conflict between two nations could quickly escalate into a wider war. This system of alliances made it difficult for countries to remain neutral and contributed to the spread of the war.
4. Lack of Effective Diplomacy: Diplomatic efforts to resolve conflicts and ease tensions failed in the years leading up to the war. The assassination of Archduke Franz Ferdinand exposed the fragility of diplomatic relations and the inability to prevent the escalation of tensions.
5. Rise of Germany and Britain as Major Powers: The emergence of Germany as a powerful industrial nation and the decline of Britain's dominance led to a shift in the European power balance and increased competition and rivalry between the two nations.
6. Pan-Slavism: Growing nationalist sentiments among Slavic populations within the Austro-Hungarian Empire posed a threat to its territorial integrity and led to tensions with Russia, which supported Pan-Slavism.
A combination of these immediate causes and long-term underlying factors contributed to the outbreak of World War I, which ultimately resulted in the loss of millions of lives, the collapse of empires, and the redrawing of political boundaries in Europe.