By the early 20th century, European nations had been largely at peace with each other for nearly 30 years. Yet, in little more than a decade, massive warfare engulfed Europe and spread across the world. World War I was started by the nationalist sentiment of the multiple nations, which led to the rise of militarism and imperialism, which ultimately led to the organization of alliance systems between nations. In the late 1800s, the idea of ​​nationalism spread across the European continent. which led the Great War, such as Russian support for the Slavic peoples, the assassination of the Archduke and the unification of Germany. With the growing desire for independence, the Slavic peoples in Bosnia and Herzegovina no longer wanted to be part of Austria-Hungary but to be part of Serbia; the Slavic people shared the same ethnicity as the Russians, so it gave the Russians a reason to support the Slavic people when they were at war (Adams, 356). In 1914, a Siberian secret society known as the Black Hand attempted to assassinate Franz Ferdinand, the Austro-Hungarian Archduke. Their accomplishment in the assassination became the catalyst that sparked disputes between the nations in Europe (Tucker, 1466). As for penalizing Serbia, the Austrian government presented the ultimatum to Belgrade on 23 July 1914; includes a long list of requests made to the Serbian government. Nationalism helped the Prussians unify its people; under the leadership of Von Bismark, Germany began to expand its territory through military might; Pan-Germanism was a movement whose goal was the political unification of all people who spoke German or a Germanic language (Ross, 455). The terminal phase of the unification of hostile activity directed towards France (Merriman, 201). The Balkan League was an alliance between Bulgaria, Serbia, Greece and Montenegro, which fought the First Balkan War against Turkey in 1912-1913 (Balkan League). Created to limit the growing Austrian power in the Balkans, the League was actually formed on Russia's initiative to expel the Turks from the Balkans (Tucker, 1534). These alliances were supposed to bring peace but in reality they were made up of endless flaws, nations fighting against each other before a deep devotion to their own nation. The fragile stability of Europe collapsed into armed conflicts, thus triggering the Great War. It is recognized that this fragile stability is triggered by patriotic devotion leading to natural rivalry for limited resources and military advancements, which was then used to protect one's nation and alliance..