What Tensions in Europe before World War 1 were most increased?

Before World War I, tensions in Europe were heightened by a complex web of alliances, militarism, nationalism, and Imperialism. The assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914 sparked a crisis, exacerbating existing rivalries, particularly between the Triple Alliance (Germany, Austria-Hungary, and Italy) and the Triple Entente (France, Russia, and Britain). Nationalistic fervor, particularly in the Balkans, along with colonial competition and military buildups, created an environment ripe for conflict, ultimately culminating in the outbreak of war.