World War I (1914-1918) was the first truly global conflict, involving over 30 nations and 70 million military personnel. The assassination of Archduke Franz Ferdinand triggered a chain reaction of alliances that engulfed the world. The Western Front in France and Belgium became synonymous with trench warfareโsoldiers lived and died in muddy ditches separated by "No Man's Land." New weapons like machine guns, poison gas, tanks, and aircraft transformed warfare forever. The war killed 17 million people, collapsed four empires, and redrew the map of Europe and the Middle East.
- 400-mile trench system from Switzerland to North Sea
- Battle of Verdun (1916): 700,000 casualties
- Battle of the Somme (1916): 1 million casualties
- Passchendaele (1917): 500,000 casualties for 5 miles
- Poison gas first used at Ypres (1915)
- Tanks debut at the Somme (1916)
- US enters war (1917), tips balance
- More mobile than Western Front, larger area
- Russia vs. Germany + Austria-Hungary
- Tannenberg (1914): Major German victory
- Brusilov Offensive (1916): Russia's last success
- Russian Revolution (1917): Russia exits war
- Treaty of Brest-Litovsk (1918): Russia loses territory
- 2 million Russian soldiers killed
- Italian Front: Alps warfare, 12 battles of Isonzo
- Gallipoli (1915-16): Failed Allied invasion of Turkey
- Middle East: Arab Revolt, Lawrence of Arabia
- African campaigns: Germany's colonies attacked
- Naval warfare: Jutland (1916), U-boat campaign
- Air warfare: First fighter planes, dogfights
- Global: Japanese seized German Pacific colonies
- German, Austro-Hungarian, Ottoman, Russian empires fall
- Treaty of Versailles (1919): War guilt, reparations
- New nations: Poland, Czechoslovakia, Yugoslavia
- League of Nations created (failed)
- Middle East carved up (Sykes-Picot)
- "Lost Generation" of young men
- Seeds of WWII planted in harsh peace terms