The Thirty Years' War lasted from 1618 to 1648 in Europe, and was one of the most destructive wars in European history, claiming around eight million lives in total. In some places half the pre-war population died and the war thoroughly influenced the Baroque Era which had prevalent themes of "vanitas" or the ultimate death and decay of all earthly things.
The war was linked to preceding and subsequent conflicts, and in the Netherlands it is known as the Eighty Years' War ending in 1648 with Dutch independence being recognized de jure.
See also: Early modern Europe
The war has its roots in the Protestant Reformation, where especially northern Europe became Protestants, and broke away from the Catholic church. The Protestant (Hussite) nobles in Bohemia rebelled against the Holy Roman Empire, which was Catholic, and ruled by the King of Austria of the House of Habsburg. While the Habsburg states included the global Spanish Empire, the anti-Habsburg alliance came to include Protestant nations such as the Netherlands and Sweden, as well as the Catholic Kingdom of France.
The Thirty Years' War was one of the first wars to be dominated by firearms, as most infantry was armed with flintlock muskets. Dragoons (soldiers who rode horses to battle and dismounted to fire their muskets) were also widely used. While the infantry was supported by pikemen to fend off cavalry, the pikes were over time replaced by bayonets. As all sides wished to field as many soldiers as possible while reducing expense, the motto was that "the war feeds itself", meaning that armies would requisition, plunder, blackmail and rob their way to the needed provisions. In short time, the common peasants came to hate all soldiers, no matter their nominal allegiance, as often the only difference was whether the soldiers would leave behind worthless scrip when they took all movable things from the local populace.
This war, like all wars in Europe into the modern era, saw a far higher proportion of soldiers die of disease than in battle, and army camps often bred various diseases, due to lacking hygiene. The firearm technology of the time, with big bullets but relatively low muzzle velocities, led to a lot of amputations, which in turn killed many soldiers when wounds became infected.
The war ended in 1648, with the Treaty of Westphalia (signed and negotiated in both Münster and Osnabrück), which established the concept of Westphalian sovereignty, the foundation of modern international relations. The basic concept is that all states would be legally equal, and should not interfere in each others' domestic affairs, where each citizen should be allegiant to no more than one ruler. This principle was an end to the Holy Roman Emperor's political influence; the title became purely ceremonial, until it was abolished in 1806. While Austria became a great power in its own right, Spain lost its role as a dominant power in Europe.
State sovereignty allowed expanded state administration, including census, postal service, banking, and military medicine. During and after the war, conscripted armed forces gradually replaced the Landsknecht (mercenary) armies.
As war between European neighbours became the exception rather than the rule, travel was less of a danger, allowing a tradition of young noblemen to go on a Grand Tour across the continent.
The Netherlands rose as a sovereign nation, experiencing the Dutch Golden Age after the war. Sweden annexed much of northern Germany, and nearly came to encircle the Baltic Sea. The Swedish dominance of the Baltic would last a century and end after the Great Northern War.
The war had a huge human toll, in Europe comparable only to the two World Wars; in some regions nearly half the population died due to the near constant fighting, plundering and diseases spread by the moving armies. Works of fiction set or written during this era often paint a grisly picture of the - very real - atrocities committed during the war, and the bleak lot of both the common soldier and regular civilians just trying to scrape by. Many geographic names that mention "Schweden" ("Sweden" or "Swedes") date back to that era and Swedish war camps.
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