How one assassination led to 2 World Wars and 100M deaths. The assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo on 28 June 1914 set off a chain reaction because Europe was already divided into rival alliances. The chain of events: - Austria-Hungary blamed Serbia. The assassin, Gavrilo Princip, was a Bosnian Serb linked to a Serbian nationalist group. Austria-Hungary wanted to crush Serbian influence in the Balkans. - Germany gave a "blank cheque." Germany promised to back Austria-Hungary, which encouraged a hard line. - Austria-Hungary issued an ultimatum to Serbia in July. Serbia accepted most demands, but Austria-Hungary declared war on 28 July. - Alliances pulled in the big powers. Russia mobilized to protect Serbia, Germany declared war on Russia and then France, and the German invasion of Belgium brought in Britain. Underlying tensions made the spark so explosive: arms races, imperial rivalries, nationalism in the Balkans, and rigid military plans like Germany's Schlieffen Plan, which assumed a fast war on two fronts and left little room for diplomacy. Thoughts?