1. Assassination of Archduke Franz Ferdinand: On June 28, 1914, Archduke Franz Ferdinand of Austria, the heir to the throne of the Austro-Hungarian Empire, was assassinated in Sarajevo by a Serbian nationalist. This event sparked a diplomatic crisis between Austria-Hungary and Serbia and ultimately led to the outbreak of World War I.
2. Declaration of War: After Austria-Hungary declared war on Serbia on July 28, 1914, a series of alliances between European nations triggered the outbreak of World War I. By early August 1914, most of Europe was embroiled in the conflict, with the major powers divided into two opposing sides: the Allies (primarily France, Britain, Russia, Italy, and the United States) and the Central Powers (Germany, Austria-Hungary, and the Ottoman Empire).
3. Schlieffen Plan: The German High Command implemented the Schlieffen Plan, an aggressive strategy to defeat France quickly before turning to face Russia on the Eastern Front. The plan involved a massive invasion of France through neutral Belgium, aiming to encircle and destroy the French army.
4. Battle of the Marne: In September 1914, the French and British forces stopped the German advance at the Battle of the Marne, effectively ending the Schlieffen Plan. The battle marked the end of the war of movement and led to a stalemate along the Western Front, characterized by trench warfare and positional deadlocks.
5. Lusitania Sinking: In May 1915, the German submarine U-20 sank the British passenger ship RMS Lusitania, killing over 1,100 people, including 128 Americans. The sinking of the Lusitania outraged the United States and contributed to the growing tensions between the U.S. and Germany.
6. Battle of Gallipoli: In April 1915, the Allied forces launched a naval and ground campaign to take control of the Gallipoli peninsula in an attempt to open up a new front against the Ottoman Empire and secure a supply route to Russia. The campaign turned into a costly and bloody stalemate, resulting in heavy losses for both sides.
7. Entry of the United States: The sinking of the Lusitania, coupled with other events such as the Zimmerman Telegram, led the United States to declare war on Germany in April 1917. The entry of the United States provided a significant boost to the Allied forces, turning the tide of the war in their favor.
8. Russian Revolution: In 1917, the Russian Empire experienced a series of revolutions that led to the overthrow of the Tsarist government and the establishment of the Bolshevik regime under Vladimir Lenin. The Russian Civil War followed, diverting significant resources and attention away from the war effort and weakening the Eastern Front.
9. Armistice: On November 11, 1918, an armistice was signed between the Allies and Germany, marking the end of World War I. The war had lasted for four years and had resulted in the deaths of millions of people, transforming the geopolitical landscape of the world.
10. Legacy and Aftermath: World War I left a lasting impact on the world. The war resulted in significant social, political, and economic changes, including the redrawing of national boundaries, the rise of communism in Russia, the decline of European empires, and the establishment of the League of Nations in an attempt to prevent future conflicts.