Final answer:
The assassination of Austrian Archduke Franz Ferdinand by Gavrilo Princip on June 28, 1914, officially started World War I. The first few months of the war were characterized by rapid military actions including trench warfare. World War I, the first truly global war, had a significant impact on people's lives worldwide and altered the course of history.
Step-by-step explanation:
The Official Start of World War I
The official start of World War I is marked by the assassination of Austrian Archduke Franz Ferdinand on June 28, 1914. The heir to the Austro-Hungarian Empire, Franz Ferdinand, was assassinated in Sarajevo by Gavrilo Princip, a member of the Serbian nationalist group known as the Black Hand. This event triggered a series of diplomatic failings and alliances that led to the outbreak of war. Princip's goal was to free Slavic peoples from Austro-Hungarian rule, but instead, the assassination led to a catastrophic global conflict.
In the first few months of World War I, known as the War of Movement, several major events unfolded rapidly. These included Germany's invasion of neutral Belgium, the Battle of the Marne which halted the German advance, and the start of trench warfare, which would become a defining characteristic of the Great War. The assassination of the Archduke set off a chain reaction that saw Austria-Hungary declaring war on Serbia, which then led Russia, Serbia's ally, to mobilize against Austria-Hungary, followed by declarations of war by Germany, France, and Great Britain.
Global Impact of World War I
World War I had a profound impact on the average citizen. It was the first truly global war due to its vast geographical scope and the involvement of countries from multiple continents. The war led to unprecedented economic strain, loss of life, and social changes. It also introduced new forms of warfare and dramatically changed the geopolitics of the world, setting the stage for future conflicts and shifting the balance of power globally.