Thirty Years' War

The Thirty Years' War (1618–1648) was a series of wars principally fought in Central Europe, involving most of the countries of Europe. It was one of the longest and most destructive conflicts in European history, and one of the longest continuous wars in modern history.

The origins of the conflict and goals of the participants were complex and no single cause can accurately be described as the main reason for the fighting. Initially, it was fought largely as a religious war between Protestants and Catholics in the Holy Roman Empire, although disputes over internal politics and the balance of power within the Empire played a significant part. Gradually, it developed into a more general conflict involving most of the great powers of the time. In this general phase the war became less specifically religious and more a continuation of the Bourbon–Habsburg rivalry for European political pre-eminence, leading in turn to further warfare between France and the Habsburg powers.

A major consequence of the Thirty Years' War was the devastation of entire regions, denuded by the foraging armies (bellum se ipsum alet). Famine and disease significantly decreased the population of the German states, Bohemia, the Low Countries, and Italy; most of the combatant powers bankrupted. While the regiments within each army were not strictly mercenary, in that they were not units for hire that changed sides from battle to battle, some individual soldiers that made up the regiments were mercenaries. The problem of discipline was made more difficult by the ad hoc nature of 17th-century military financing; armies were expected to be largely self-funding, by means of loot taken or tribute extorted from the settlements where they operated. This encouraged a form of lawlessness that imposed severe hardship on inhabitants of the occupied territory.

The Thirty Years' War was ended with the treaties of Osnabrück and Münster, part of the wider Peace of Westphalia. Some of the quarrels that provoked the war went unresolved for a much longer time.