1)World WarI began in 1914, after the assassination of Archduke Franz Ferdinand, and lasted until 1918. During the conflict, Germany, Austria-Hungary, Bulgaria and the Ottoman Empire (the Central Powers) fought againstGreatBritain, France, Russia, Italy, Romania, Japan and the United States (the Allied Powers).

2)number of alliances involving European powers, theOttoman Empire, Russia and other parties had existed for years, but political instability in theBalkans(particularly Bosnia, Serbia and Herzegovina) threatened to destroy these agreements.

The spark that ignited World War I was struck in Sarajevo, Bosnia, whereArchduke Franz Ferdinand—heir to the Austro-Hungarian Empire—was shot to death along with his wife Sophie by the Serbian nationalistGavrilo Principon June 28, 1914. Princip and other nationalists were struggling to end Austro-Hungarian rule over Bosnia and Herzegovina.

The assassination of Franz Ferdinand set off a rapidly escalating chain of events:Austria-Hungary, like many in countries around the world, blamed the Serbian government for the attack and hoped to use the incident as justification for settling the question of Serbian nationalism once and for all.