French soldiers sing the national anthem at the beginning of World War I in August 1914. This "war to end all wars" might seem like ancient history, but it changed the world forever. It transformed the way war was fought, upended cultures and home life and stimulated innovations that affect us today. With more than 30 combatant nations and nearly 70 million men mobilized, World War I profoundly destabilized the international order. Look back at some of the war's key events.
French soldiers sing the national anthem at the beginning of World War I in August 1914. This "war to end all wars" might seem like ancient history, but it changed the world forever. It transformed the way war was fought, upended cultures and home life and stimulated innovations that affect us today. With more than 30 combatant nations and nearly 70 million men mobilized, World War I profoundly destabilized the international order. Look back at some of the war's key events.
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The bodies of Austria-Hungary Archduke Franz Ferdinand and his wife, Sophie, Duchess of Hohenberg, are seen after their assassination by Serbian nationalist Gavrilo Princip on June 28, 1914. The assassination led Austria-Hungary to declare war on Serbia, starting a chain of events that would gradually bring other nations into the fray.
The bodies of Austria-Hungary Archduke Franz Ferdinand and his wife, Sophie, Duchess of Hohenberg, are seen after their assassination by Serbian nationalist Gavrilo Princip on June 28, 1914. The assassination led Austria-Hungary to declare war on Serbia, starting a chain of events that would gradually bring other nations into the fray.
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Germans in Berlin mobilize for war on August 1, 1914. Germany was a strong ally of Austria-Hungary.
Germans in Berlin mobilize for war on August 1, 1914. Germany was a strong ally of Austria-Hungary.
DPA/picture-alliance/AP
French soldiers are seen at a front-line trench in Italy. During World War I, the Allied Powers consisted of Belgium, France, Great Britain, Greece, Italy, Montenegro, Portugal, Romania, Russia, Serbia and the United States. The Central Powers consisted of Austria-Hungary, Bulgaria, Germany, and Ottoman Empire (now Turkey).
French soldiers are seen at a front-line trench in Italy. During World War I, the Allied Powers consisted of Belgium, France, Great Britain, Greece, Italy, Montenegro, Portugal, Romania, Russia, Serbia and the United States. The Central Powers consisted of Austria-Hungary, Bulgaria, Germany, and Ottoman Empire (now Turkey).
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German soldiers captured by the British are seen in France.
German soldiers captured by the British are seen in France.
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Men visit the graves of French soldiers killed in the Battle of the Marne in September 1914.
Men visit the graves of French soldiers killed in the Battle of the Marne in September 1914.
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Troops land at Anzac Cove in the Dardanelles during the battle between Allied forces and Turkish forces at the Gallipoli Peninsula in February 1915. The two sides were fighting for access to the strategic Sea of Marmara and eventually to Constantinople (Istanbul).
Troops land at Anzac Cove in the Dardanelles during the battle between Allied forces and Turkish forces at the Gallipoli Peninsula in February 1915. The two sides were fighting for access to the strategic Sea of Marmara and eventually to Constantinople (Istanbul).
Corbis
German and British troops are seen together during the Christmas Truce of 1914.
German and British troops are seen together during the Christmas Truce of 1914.
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These French Zouave infantrymen were killed by gas during the Second Battle of Ypres, Belgium, in April 1915.
These French Zouave infantrymen were killed by gas during the Second Battle of Ypres, Belgium, in April 1915.
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Germans give oxygen to a gas victim in 1915. The cloth masks worn by these soldiers provided little defense; more substantial gas masks were not produced until 1916. By the end of the war, even horses and dogs used at the front had their own gas masks.
Germans give oxygen to a gas victim in 1915. The cloth masks worn by these soldiers provided little defense; more substantial gas masks were not produced until 1916. By the end of the war, even horses and dogs used at the front had their own gas masks.
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German U-boats, or submarines, patrol the Mediterranean coast.
German U-boats, or submarines, patrol the Mediterranean coast.
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French troops rest in Verdun, France, in 1916. Verdun was the site of the longest battle of World War I.
French troops rest in Verdun, France, in 1916. Verdun was the site of the longest battle of World War I.
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Dead bodies lie piled in a trench at Verdun on April 9, 1916.
Dead bodies lie piled in a trench at Verdun on April 9, 1916.
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British troops advance during the Battle of the Somme in 1916.
British troops advance during the Battle of the Somme in 1916.
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A British tank is stranded while crossing a trench during the Battle of the Somme on September 25, 1918.
A British tank is stranded while crossing a trench during the Battle of the Somme on September 25, 1918.
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German soldiers stand near a crashed fighter plane in Germany in 1916.
German soldiers stand near a crashed fighter plane in Germany in 1916.
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Czar Nicholas II of Russia, right, reviews the palace guard just prior to the Russian Revolution of 1917.
Czar Nicholas II of Russia, right, reviews the palace guard just prior to the Russian Revolution of 1917.
AP
U.S. President Woodrow Wilson addresses a joint session of Congress in April 1917, requesting a declaration of war on Germany. The United States declared war against Germany after the interception and publication of the Zimmermann Telegram and the sinking of three U.S. merchant ships by German U-boats.
U.S. President Woodrow Wilson addresses a joint session of Congress in April 1917, requesting a declaration of war on Germany. The United States declared war against Germany after the interception and publication of the Zimmermann Telegram and the sinking of three U.S. merchant ships by German U-boats.
AP
Britons stand in line outside an Army recruiting station.
Britons stand in line outside an Army recruiting station.
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A British sergeant major instructs American soldiers in bayonet fighting at Texas' Camp Dick.
A British sergeant major instructs American soldiers in bayonet fighting at Texas' Camp Dick.
Corbis
U.S. Army troops stand in a defensive trench in France. By war's end, thousands of miles of trenches crisscrossed European battlefields.
U.S. Army troops stand in a defensive trench in France. By war's end, thousands of miles of trenches crisscrossed European battlefields.
AP
A defeated German army marches home on October 1, 1918.
A defeated German army marches home on October 1, 1918.
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Armistice Day is celebrated in Chicago on November 1, 1918.
Armistice Day is celebrated in Chicago on November 1, 1918.
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U.S. troops returning home from France are seen on the USS Agamemnon in Hoboken, New Jersey, in 1919.
U.S. troops returning home from France are seen on the USS Agamemnon in Hoboken, New Jersey, in 1919.
Getty Images
German delegates listen to French Prime Minister Georges Clemenceau's speech during the signing of the Treaty of Versailles in France on June 28, 1919.
German delegates listen to French Prime Minister Georges Clemenceau's speech during the signing of the Treaty of Versailles in France on June 28, 1919.
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