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Archduke Franz Ferdinand of Austria-Hungary and his wife Sophie were assassinated in Sarajevo by Gavrilo Princip, a Serbian nationalist. This event triggered a chain reaction of alliances and declarations of war, starting World War I. -
World War I (1914-1918), also known as the Great War, was a global conflict that pitted the Allied Powers (including Great Britain, France, Russia, and the United States) against the Central Powers (including Germany, Austria-Hungary, and the Ottoman Empire). Triggered by the assassination of Archduke Franz Ferdinand, the war was characterized by new weaponry like tanks and poison gas, trench warfare, and unprecedented casualties, ending in November 1918 with the defeat of the Central Powers.
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After sending Serbia an ultimatum with harsh demands (which Serbia partly rejected), Austria-Hungary declared war. This marks the official start of World War I. -
August 1: Germany declares war on Russia (Serbia’s ally). August 3: Germany declares war on France. August 4: The United Kingdom declares war on Germany after it invades Belgium. The alliance system (Triple Entente vs. Central Powers) transforms a local conflict into a world war. -
Germany invaded neutral Belgium to reach France quickly (the Schlieffen Plan). Britain declared war on Germany the same day, expanding the conflict into a full-scale world war. -
Fought on the Eastern Front between Germany and Russia. Germany wins a decisive victory, capturing tens of thousands of Russian soldiers. Establishes the fame of German generals Hindenburg and Ludendorff. -
German troops advance to within 40 km of Paris, but French and British forces manage to stop them. The battle halts the German advance and leads to the creation of trench warfare on the Western Front. -
Heavy fighting in Belgium results in huge casualties on both sides. Marks the end of mobile warfare and the beginning of a long, static trench war. -
The Ottoman Empire joins Germany and Austria-Hungary to form the Central Powers. The war expands to the Middle East, the Caucasus, and Africa. -
Fought in Belgium, this battle is notable for Germany’s first large-scale use of poison gas (chlorine). Many soldiers die or are injured due to gas exposure. The use of chemical weapons adds a new level of horror to the war. -
Italy leaves the Triple Alliance (with Germany and Austria-Hungary) and joins the Allies after being promised land gains. New fighting begins along the Italian Front in the Alps. -
A German U-boat torpedoes the British passenger liner RMS Lusitania off the coast of Ireland.
Nearly 1,200 civilians die, including 128 Americans. The attack turns world opinion against Germany and increases pressure on the U.S. to join the war. -
Germany intensifies submarine attacks in the Atlantic, targeting Allied supply ships. On the Western Front, both sides remain locked in trench warfare, with little territorial change despite heavy casualties. -
Germany launches a massive attack against French forces at Verdun. The battle lasts 10 months, becoming one of the longest and bloodiest of the war. French motto: “They shall not pass!” Result: France holds Verdun, but both sides suffer over 700,000 casualties. -
The only major naval battle between Britain’s Royal Navy and Germany’s High Seas Fleet. Both sides claim victory: Britain keeps control of the seas, but Germany inflicts heavy damage. Confirms Britain’s naval dominance for the rest of the war. -
One of the bloodiest battles in history, fought between British/French forces and Germany along the Somme River in France. Over 1 million soldiers were killed or wounded; it showed how deadly trench warfare had become. It ended in November 18 of 1916 -
The U.S. declared war on Germany after repeated submarine attacks on American ships and the interception of the “Zimmermann Telegram".
The arrival of fresh U.S. troops and resources helped the Allies turn the tide of the war. -
(April–June)
The French launch the Nivelle Offensive on the Western Front, promising a quick victory. It fails badly, causing massive French casualties. Many soldiers mutiny, refusing to attack again; discipline is later restored by General Pétain. -
A major Allied offensive in Belgium, fought in horrible mud and rain. Gains only a few miles of ground for hundreds of thousands of casualties. Symbol of the futility and suffering of trench warfare. -
The Bolsheviks, led by Vladimir Lenin, seize power in Russia. Russia begins peace talks with Germany, effectively leaving the war soon after. -
British forces use tanks on a large scale for the first time. The attack initially succeeds but later loses momentum. Shows that tanks could break trench lines when properly used. -
Germany attacks on the Western Front before U.S. troops fully arrive. They make big advances but cannot achieve a decisive victory. The German army becomes exhausted and short on supplies. -
Germany makes its last major offensive but is stopped by French, British, and newly arrived American forces. Marks the turning point of the war — Germany begins to retreat. -
The Allies launch a powerful counterattack using tanks, aircraft, and infantry coordination. German morale collapses; Ludendorff calls it the “Black Day of the German Army.” Starts the Hundred Days Offensive. -
The largest Allied offensive on the Western Front, involving over a million U.S. soldiers. The Germans are pushed back toward their borders. Their defeat becomes inevitable. -
What happened: Germany signed an armistice agreement with the Allies, ending the fighting on the Western Front. This day marked the official end of World War I and is now remembered as Armistice Day or Veterans Day.