About 3,930,000 results
World War I: Summary, Causes & Facts - HISTORY
World War I - Wikipedia
Causes of World War I - Wikipedia
World War I | History, Summary, Causes, Combatants, Casualties, …
8 Events that Led to World War I - HISTORY
World War I: Causes and Timeline - HISTORY
World War I 1914-1918 - Encyclopedia Britannica
Causes and Effects of World War I - Encyclopedia Britannica
BBC - History - World Wars: The Origins of World War One
World War I facts and information - National Geographic