The Spark in Sarajevo
Europe in 1914 was a powder keg of secret alliances, imperial rivalries, and fervent nationalism. The spark came on June 28, 1914, in Sarajevo, Bosnia. Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, was assassinated by Gavrilo Princip, a Serbian nationalist.
This single gunshot triggered a domino effect. Austria-Hungary declared war on Serbia. Russia mobilized to protect Serbia. Germany declared war on Russia and its ally France. When German troops marched through neutral Belgium to attack France (the Schlieffen Plan), Great Britain declared war on Germany.
In just six weeks, a regional Balkan crisis had exploded into a devastating global conflict involving all the world's great powers.