This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
When the Bohemian estates threw two Habsburg officials from a window in Prague Castle in May 1618, nobody present could have known they had opened a war that would run for thirty years and reach every corner of the continent. What began as a local revolt against Habsburg rule and Catholic pressure on a Protestant kingdom widened, as Denmark entered in 1625, Sweden in 1630 and France in 1635, into something closer to a European war fought on German soil, over a German constitutional question, by armies that were increasingly foreign to it.
The toll is still argued over, and honestly so. General estimates put total deaths, from combat, disease and the famine that followed the collapse of civil order, somewhere between four and a half and eight million, concentrated overwhelmingly in the Holy Roman Empire itself. Whole regions lost a quarter or more of their population, not mostly to soldiers' swords but to the things that follow armies: typhus, plague, and fields left unplanted while men who would have worked them were levied, killed, or fled.
What historians increasingly agree on is what the war was actually about at its core: not simply Catholic against Protestant, but the German princes' resistance to an emperor who wanted to rule the Empire as a unified, centralised state on the French or Spanish model. That is why the Peace of Westphalia, signed in October 1648 across two Westphalian towns, mattered so far beyond ending one war. It confirmed the princes' effective sovereignty within their own territories, recognised Calvinism alongside the two confessions the 1555 Peace of Augsburg had already tolerated, and froze the Empire's religious map for a century and a half. Later writers on international law read Westphalia as the moment the modern idea of the sovereign state, answerable to no higher authority within its own borders, became Europe's working principle rather than an aspiration. Whether that reading gives one treaty too much credit for a change already under way is itself a live argument among historians, but the settlement's name has become a shorthand for the idea regardless.