Historians identify nationalism and militarism, alongside complex alliances, as fundamental causes of World War I. Nationalism fueled rivalries and a competitive spirit among European nations, leading to heightened tensions and conflicts over territory and influence. Militarism contributed to an arms race, with countries building up their military capabilities, creating an environment ripe for conflict. The tangled web of alliances, such as the Triple Alliance and the Triple Entente, meant that a localized conflict could quickly escalate into a full-scale war, ultimately triggered by the assassination of Archduke Franz Ferdinand of Austria in 1914.