World War I

World War I — known to those who lived through it simply as "The Great War" — began with a single assassination in Sarajevo on June 28, 1914, and ended with the deaths of an estimated 17 to 22 million people and the collapse of four empires. It was the first conflict in history to be described as a world war not as hyperbole but as sober fact: fighting occurred on the Western Front in France and Belgium, the Eastern Front across Russia and Ukraine, the Italian Front, the Mesopotamian and Palestinian campaigns, and at sea across the globe. In four years, it killed more people than any previous conflict in European history.

The war's defining characteristic was the catastrophic mismatch between 19th-century military tactics and 20th-century industrial weapons. Generals on all sides initially planned for mobile, decisive campaigns — the German Schlieffen Plan, for instance, called for defeating France in six weeks and then turning east against Russia. Instead, the Western Front stabilized into 700 kilometers of trenches by late 1914, and would barely move for the next three years. The reason was firepower. Machine guns could fire 600 rounds per minute, making frontal infantry assaults suicidal. Artillery had become capable of destroying entire landscapes — the Battle of the Somme opened with a week-long artillery barrage that fired 1.5 million shells, yet failed to destroy the German defenses. The first day of the Somme, July 1, 1916, saw 57,470 British casualties including 19,240 killed — the bloodiest single day in the history of the British Army.

Both sides introduced new weapons in desperate attempts to break the stalemate. Poison gas — first used at scale by Germany at Ypres in April 1915 — caused agonizing deaths from chlorine and mustard gas exposure, and left survivors with lifelong respiratory damage. Tanks, introduced by the British in 1916, promised mobility but were mechanically unreliable. Aircraft evolved from reconnaissance platforms to fighters and bombers within four years. Submarines threatened to starve Britain by sinking merchant shipping and ultimately brought the United States into the war when Germany's unrestricted submarine warfare sank American vessels.

The human cost was distributed across all belligerents. France lost approximately 1.4 million soldiers killed; Germany, 2 million; Russia, 1.8 million before its revolution and withdrawal in 1917; Austria-Hungary, 1.5 million; Britain and its Empire, 900,000; the Ottoman Empire, roughly 800,000. Total civilian deaths — from bombardment, famine, disease, and the Armenian Genocide — added millions more. The Spanish Flu, which erupted in the final year of the war and was accelerated by the movement of troops across the globe, killed more people than the fighting itself.

The war's political consequences reshaped the world. The Austro-Hungarian, Russian, German, and Ottoman empires all collapsed. The Treaty of Versailles imposed punishing reparations on Germany that economists like John Maynard Keynes predicted would destabilize Europe — a prophecy fulfilled when the humiliation and economic chaos helped bring Adolf Hitler to power 14 years later. The League of Nations, created to prevent future wars, lacked enforcement mechanisms. World War I did not end wars; it made World War II almost inevitable.