WW1 was declared on june 28, 1914 in Sarajevo, Bosnia and hercegovina
WW1 started because of the assassination of Franz Ferdinand, he was killed by a Bosnian-Serb
Wife of Franz Ferdinand
The first attempt of his assassination failed when one of the Bosnian-Serb threw a bomb at the archduke but failed due to the bomb hitting his car instead
By 1914, those alliances resulted in the six major powers of Europe coalescing into two broad groups: Britain, France and Russia formed the Triple Entente, while Germany, Austria-Hungary and Italy comprised the Triple Alliance.