World War I is probably one of the biggest wars that contained so much "chain reaction". One
             feels threatened, they ally with their friends, and another nation feels threatened, so they ally with
             their friends. The feeling of threat leads into invasions then leads into their allies helping and invading
             and pretty soon, more allies come from both sides. Some would argue that the assassination of a leader
             in Europe caused the war to happen, that person being Archduke Franz Ferdinand. However, war like
             this was started even before they called it World War I. In a 1915 issue of the Clock Magazine, it
             states, "It is thought that this war that has been ongoing for over a year, began with the assassination
             of the Archduke Francis Ferdinand. However, many other reasons led to this war, some occurring as far
             back the late 1800's. Nationalism, militarism, imperialism, and the system of alliances were four main
             factors that pressed the great powers towards this explosive war." (Clock Magazine 1915 Aug. 17) Yes
             Francis Ferdinand was assassinated and sparked the beginning of the war, but that was not the main
             cause. The four major roles that played in the cause of World War I were Nationalism, Militarism,
             Imperialism, and the Alliance System.
             Nationalism: a philosophy that is purely focused on patriotism, loyalty to one's nation and
             seeing its nation as the superior nation. Such philosophy remained popular around this time. In fact,
             it's popularity started in late 1800's. Most countries in Europe were nationalistic about their country
             and wanted their country to have strict culture and language system. Some countries even tended to
             take aggresional means of nationalism by wanting to get rid of inferior and small countries and convert
             them to their own culture, this is much like a monopoly in an industry, the stronger prevales. Such
             ideas threatened countries tha...