What allowed for the small scale war in the Balkans to lead to a much larger World War

Explanation:

Many attribute the escalation of ww1 and the events of the July crisis to complicated networks of alliances that were the keystone of European Diplomacy at the time. Compounded with the leaders of countries who each believed they would win the war quickly, and technological advancements since the Franco-prussian war, the conflict in the Balkans quickly escalated to a large scale war.