Final answer:
The assassination of Austrian Archduke Franz Ferdinand on June 28, 1914, by a Serbian nationalist was the immediate cause of World War I. The subsequent involvement of European powers due to intricate alliances transformed a regional conflict into a global war. Nationalism, militarism, and imperial ambitions also played crucial roles in the lead-up to the conflict.
Step-by-step explanation:
The Assassination that Sparked World War I
The event that triggered the start of World War I was the assassination of Austrian Archduke Franz Ferdinand on June 28, 1914. The Archduke, who was the heir to the Austro-Hungarian throne and a proponent of peaceful diplomacy, was killed by Gavrilo Princip, a young Serbian nationalist. This assassination set off a chain reaction among the major powers of Europe.
The First Few Months of World War I
Following the assassination, Austria-Hungary made demands on Serbia, which when not fully met, led to Austria's declaration of war on Serbia. Germany, as an ally of Austria-Hungary, supported the invasion, which then activated the network of alliances throughout Europe. Russia mobilized in support of Serbia, France backed Russia, and Britain, allied with France, eventually entered the war. These alliances transformed a regional conflict into a full-scale global war, involving colonies and territories far beyond the European borders.
Nationalism was also a key factor that fed the tensions leading to the war, alongside militarism, imperial ambitions, and political alliances. The assassination of Franz Ferdinand was the 'spark' amidst these volatile conditions that led to the outbreak of World War I, marking it as the first global conflict and altering the lives of the average citizen.