Events leading to World War 1
1. Austria-Hungary annexed Bosnia and Herzegovina in 1908
2. Serbian nationalism movement wanted control over this region
3. Archduke Franz Ferdinand assassinated in Sarajevo on June 28, 1914
4. Austria-Hungary presented an ultimatum to Serbia on July 23, 1914
5. Austria-Hungary declared war on Serbia on July 28, 1914
6. Russia declared war the same day, and mobilization began