Assassination of Archduke Franz Ferdinand
Sinking of the Lusitania
Treaty of Versailles
Zimmermann Telegram
Treaty of Versailles
Treaty of Ghent
Treaty of Paris
Treaty of Tordesillas
Russia
United Kingdom
Austria-Hungary
Germany
Battle of the Marne
Battle of Verdun
Battle of the Somme
Battle of Passchendaele
Woodrow Wilson
Franklin D. Roosevelt
Theodore Roosevelt
Warren G. Harding
Trench warfare
Air warfare
Guerrilla warfare
Naval warfare