A Bohemian window toss ignited thirty years of war
Between 1618 and 1648, Central Europe bled through battle, famine, and disease; estimates put deaths at 4.5 to 8 million, with some German regions losing more than half their people. Faith mattered—but French–Habsburg rivalry and the Dutch revolt made the fire continental.
The Thirty Years' War began when Protestant nobles in Prague defenestrated Emperor Ferdinand II's Catholic agents in May 1618 and replaced him as Bohemia's king with Calvinist Frederick V of the Palatinate. Ferdinand was swiftly restored, yet fighting spilled into the strategically vital Palatinate, pulling in Spain and the Dutch Republic already locked in the Eighty Years' War. Danish and Swedish interventions followed. From 1618 to 1635 the struggle was mainly an imperial civil war, largely settled by the Peace of Prague—until France entered beside Sweden and turned Germany into one front against Habsburg Spain and Emperor Ferdinand III.
Religious settlement had been fragile since the 1555 Peace of Augsburg, which assigned each state Lutheran or Catholic status under cuius regio, eius religio. Calvinism's spread after 1555, plus disputes over church property and imperial power, eroded that bargain. Roughly 300 imperial estates—from seven electors down to free cities—operated in separate Imperial Circles, while the Diet talked more than it legislated. Habsburgs had held the emperorship since 1440, ruling some eight million subjects in Austria, Bohemia, and Hungary, and remaining tied to Spanish wealth until subsidies faded after 1640.
Prewar flashpoints included the 1606 Donauworth flag riots, the Protestant Union of 1608, the Catholic League of 1609, and the Julich succession war of 1609–14. Spain needed the Spanish Road through the Palatinate before the Twelve Years' Truce expired. The 1648 Peace of Westphalia enlarged the autonomy of states such as Bavaria and Saxony, gave Sweden northern German gains, and forced Spain to accept Dutch independence—closing a war that began as a local dynastic revolt and ended as a remaking of European order.
Source: Thirty Years' War
