In the decades before 1914, Europe split into two rigid military blocs—the Triple Alliance and the Triple Entente—transforming regional rivalries into a system that made a general war inevitable. Driven by militarism, intense naval competition, and Balkan instability, these alliance systems quickly escalated the 1914 Sarajevo assassination into a global conflict. For an overview of these alliances, visit Imperial War Museums . What You Need To Know About Pre-First World War Alliances