The major causes of the Great War (1914-1918) were Nationalism, Imperialism, Alliances, and Militarism. These were long-term issues and built tension between nations over the years. The assassination of Arch-Duke Ferdinand was a short-term cause that acted as a trigger that ignited the powder keg of Europe nations and put into motion the complicated set of alliances that forced nations into war. Nationalism is the extreme sense of pride in your nation and the promotion of your national interests