Fact: The assassin was Gavrilo Princip, a Bosnian Serb nationalist. Fun fact: The Archduke survived the first assassination attempt (a grenade bounced off his car) but was shot later when his driver took a wrong turn and stopped near Princip. The alliance system (Triple Alliance vs. Triple Entente) turned a local conflict into a world war. European armies doubled in size between 1890-1914, and military spending increased 300%.

Fact: The Western Front was a stalemate; front lines moved little despite millions of casualties. Fun fact: From 1914-1918, the front line averaged only 200 yards of movement per month of fighting. The Battle of the Somme (1916) gained 6 miles at the cost of 1 million casualties. Soldiers lived in muddy, rat-infested trenches with "trench foot," lice, and constant shelling. "No Man's Land" between trenches varied from 100-400 yards wide.

Fact: The US declared war on Germany on April 6, 1917. Fun fact: The Zimmermann Telegram proposed Mexico attack the US to reclaim Texas, New Mexico, and Arizona. British intelligence intercepted and decoded the telegram, then revealed it to the US. President Woodrow Wilson won re-election in 1916 on the slogan "He kept us out of war." US troops arrived in France in 1917, but significant combat began in 1918. The American Expeditionary Force numbered 2 million soldiers.

Fact: Gas casualties: 1.3 million, with 90,000 deaths. Fun fact: The Germans first used chlorine gas at Ypres (1915). Mustard gas (introduced 1917) caused severe burns but only 2-3% mortality. Gas masks became standard issue, using charcoal filters and goggles. Horses and mules (8 million used) wore gas masks too. The soldier's urine could react with chlorine to create a crude decontaminant. Artillery shells produced 70% of all wounds, shrapnel the rest.

Fact: German Chief of Staff Falkenhayn planned to attack a symbolically important fortress (Verdun) that France would defend at any cost. Fun fact: The battle lasted 10 months (February-December 1916). Casualties: approximately 400,000 French and 350,000 German. The French motto "Ils ne passeront pas!" (They shall not pass!) originated here. The battle destroyed nine villages that were never rebuilt. Average artillery density: 1 gun per every 2 yards of front.

Fact: The name "tank" was a security cover—they were shipped in crates labeled "water tanks." Fun fact: The first tanks (Mark I) weighed 28 tons, had a top speed of 3.7 mph, and required a crew of 8. Of the 49 tanks deployed at the Somme, only 25 reached the start line, and mechanical failures disabled most. By 1918, tanks like the Renault FT (lighter, with a rotating turret) proved decisive. Germany produced only 20 tanks vs. Britain's 2,600.

Fact: The armistice was signed at 5:00 AM in a railroad car at Compiègne, France, effective 11:00 AM. Fun fact: In the final six hours, 11,000 soldiers were killed or wounded, including 2,738 Americans. Private Henry Gunther, killed at 10:59 AM, is considered the last combat death. The Germans were starving; the British naval blockade had caused 500,000 German civilian deaths. The last soldier killed was Canadian Private George Price at 10:58 AM.

Fact: The Treaty of Versailles (1919) forced Germany to pay 132 billion gold marks (about $33 billion). Fun fact: Germany's military was limited to 100,000 troops, no tanks, air force, or submarines, and lost 13% of its territory. Adolf Hitler, a WWI corporal, was poisoned by mustard gas in 1918. The "Stab-in-the-back" myth falsely claimed German politicians betrayed the undefeated army. The League of Nations, created after WWI, failed to prevent WWII due to lacking an army.

Fact: The truce occurred spontaneously along parts of the Western Front on Christmas Eve/Day 1914. Fun fact: Soldiers exchanged chocolate, cigarettes, and buttons. One reported football match ended 3-2 for the Germans. High commands were furious and banned fraternization; such truces never happened again on this scale. About 100,000 soldiers participated. The truce showed common humanity despite the war's brutality. Many soldiers refused to fight the next day, but officers forced them.

Fact: Civilian deaths (from famine, disease, and atrocities) added 5-10 million more. Fun fact: The average life expectancy of a British officer on the Western Front was 6 weeks. 20% of French soldiers (ages 18-30) died. Russia mobilized 12 million soldiers—the largest army—and suffered 9 million casualties. The Battle of the Somme (1916) alone had 1 million casualties on both sides. The war destroyed 30,000 square miles of French farmland and 6,000 factories.