Bing found the following results
World War I: Summary, Causes, Facts & Dates | HISTORY
World War I - Wikipedia
World War I | History, Summary, Causes, Combatants ... - Britannica
World War I: Causes and Timeline | HISTORY
World War I | Britannica
World War I | Key Facts | Britannica
World War I facts and information - National Geographic
World War I Timeline: Battles & Major Events - HISTORY
Causes of World War I - Wikipedia
How and why did World War One start? - BBC Bitesize