On this day in 1914, in Sarajevo, a Serbian nationalist shot and killed Archduke Franz Ferdinand, heir to the throne of the Austria-Hungary Empire, and his expectant wife, Sophie, Duchess of Hohenberg. The assassin was 19-year-old Gavrilo Princip, one six Bosnian Serbs trained by Serbian military officers.

One month after the two were murdered, World War I began. Scholars continue to debate why exactly the war started. There had been diplomatic skirmishes since the mid-1800s in Europe. 

One immediate cause was territorial disputes in the Balkans. Austria-Hungary struggled again Serbia and Russia for territory and influence in the region. Through treaties, alliances and family ties, they pulled the rest of the Great Powers into the conflict

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