There were three main causes leading up to World War 1, but it wasnt until June 28, 1914 the assassination of Archduke Franz Ferdinand triggered World War 1 which began on July 28, 1914. .
The main causes leading of World War 1 were: The Rise of Nationalism, Build-up of Military might, and system of military alliances. Europe avoided major wars in the 100 years before world War 1 began. In the 1800's, nationalism swept across the continent that help bring about the Great War. Nationalism led to the creation of two new powers - Italy and Germany - through the uniting of several small states. On the other hand, nationalism weakened the eastern European empires of Austria-Hungary, Russia, and Ottoman Turkey. Those empires ruled many national groups that wanted independence. Tensions began that threatened to ignite a major war. Rivalry for control of the Balkans added to the tensions that erupted into World War 1. A build-up of military might occurred among European countries before World War 1 broke out. Nationalism encouraged public support for military build-ups and for a countries use of force to achieve it's goals. By the end of the 1800's, technology enabled countries to fight longer and have greater losses than ever before. A system of military alliances gave European powers a sense of security before World War 1 broke out. They formed alliances with each other for protection and guarantee that other members of the alliance would come to the countries aid if attacked. Although alliances provided protection, the system also created some dangers. If war came, the alliance system meant that a number of nations would fight, not only the two involved in the argument. Alliances could cause a country to go to war against a country it had no argument with. In addition, the terms of many alliances were kept secret. The secrecy also increased the chances that a country might guess wrong about the consequences of their actions.