What were some major causes of World War I?

Some long-term causes that had been building for a long time include alliances that would pull countries into battle - before WWI, there were alliances between Japan and Britain, Russia and Serbia, France and Russia, Germany and Austra-Hungary and Britain and France and Belgium. This meant that when Austria-Hungary declared war on Serbia, Russia got involved to defend Serbia. Germany this saw Russia as a threat and declared war on them so France was drawn in to defend Russia. Germany attacking France thus brought both Britain and Japan into the war. There was also a great increase in militarism as demonstrated between the arms race between Britain and Germany that helped push the countries into war. Nationalism can be seen as both a long-term and short-term cause of war. Long-term in the sense that it contributed to the war and the extension of the war with each country trying to push their dominance over the others. Short-term in the sense that Slavic people in Bosnia and Herzegovina wanted to be a part of Serbia. A short-term cause was the assassination of Archduke Franz Ferdinand. Everything had been building for a number of years and this assassination was the breaking point that caused the war.