The immediate cause of the first world war was an important event called the Sarajevo crisis that took place someday towards the end of June, 1914[NOTE: a few days more than a century back,today its 2014]. The Archduke francis ferdinand of austria and his wife were assasinated at sarajevo, the capital city of bosnia. the austrian government considered it to be a violent action by the serbian government. so she asked serbia to hand over the criminals to her. however, the serbian government refused to do so on account of violation of its sovereignty. this was the spark for lighting up the first world war. Two opposite forces had already been formed:
TRIPLE ALLIANCE: BRITAIN, FRANCE AND GERMANY(which supported serbia)
TRIPLE ENTENTE: RUSSIA, ITALY, AUSTRIA-HUNGARY
the war began between these forces which soon spread throughout the world.