- 
  
   He was assassinated in Sarajevo, most likely by the Serbians. He was assassinated in Sarajevo, most likely by the Serbians.
- 
  
   Austria-Hungary declares war on Serbia. Austria-Hungary declares war on Serbia.
- 
  
    
- 
  
   German forces shock Allied soldiers along the Western Front by firing more than 150 tons of lethal chlorine gas against two French colonial divisions at Ypres in Belgium. German forces shock Allied soldiers along the Western Front by firing more than 150 tons of lethal chlorine gas against two French colonial divisions at Ypres in Belgium.
- 
  
   The Allies launched their invasion of the Gallipoli Peninsula The Allies launched their invasion of the Gallipoli Peninsula
- 
  
    
- 
  
   The British government authorized the evacuation to begin from Suvla Bay on December 7; the last troops left Helles on January 9, 1916. The British government authorized the evacuation to begin from Suvla Bay on December 7; the last troops left Helles on January 9, 1916.
- 
  
   British empire fights the German empire alongside the French Third Republic. British empire fights the German empire alongside the French Third Republic.
- 
  
   British cryptographers deciphered a telegram from German Foreign Minister Arthur Zimmermann to the German Minister to Mexico, Heinrich von Eckhardt, offering United States territory to Mexico in return for joining the German cause. British cryptographers deciphered a telegram from German Foreign Minister Arthur Zimmermann to the German Minister to Mexico, Heinrich von Eckhardt, offering United States territory to Mexico in return for joining the German cause.
- 
  
    
- 
  
   Ended Russia's participation in WW1 Ended Russia's participation in WW1
- 
  
   The treaty forced Germany to surrender colonies in Africa, Asia and the Pacific The treaty forced Germany to surrender colonies in Africa, Asia and the Pacific