1. Imperialism and Nationalism: The rivalry among European powers for colonies and resources, combined with growing nationalism and the desire for territorial expansion, created tensions and increased the likelihood of conflict.
2. Alliances and Entanglements: The system of alliances between the European powers, such as the Triple Entente (Britain, France, and Russia) and the Triple Alliance (Germany, Austria-Hungary, and Italy), created a web of obligations that made it difficult to defuse tensions without escalating into a wider conflict.
3. Arms Race: The intense arms buildup among European nations in the years leading up to the war created a climate of fear and suspicion. The competition to outmatch one another in military strength further heightened tensions.
4. Bosnian Crisis and Assassination of Archduke Franz Ferdinand: The annexation of Bosnia and Herzegovina by Austria-Hungary in 1908 and the assassination of Archduke Franz Ferdinand in 1914 were the immediate triggers that set off a chain of events leading to the outbreak of war.
5. Militarism and Crisis Management: The prevalence of militaristic cultures, the influence of military elites in policymaking, and the inadequate diplomatic mechanisms to manage crises contributed to the failure to resolve tensions peacefully.
It's important to note that these factors are not mutually exclusive, and their interplay led to the outbreak of World War I. The specific combinations of causes and their relative importance have been debated among historians for decades.