- The Thirty Years War is one of the great conflicts of early modern European history.
- It consisted of a series of declared and undeclared wars which raged through the years 1618-1648 throughout central Europe.
- During the Thirty Years War the opponents were, on the one hand, the House of Austria: the Habsburg Holy Roman Emperors Ferdinand II and Ferdinand III together with their Spanish cousin Philip IV.
- During the long course of the Thirty Years War the Habsburgs were opposed by various international opponents of House of Austria: the Danish, Dutch and, above all, France and Sweden.
- In addition to its international dimensions the Thirty Years War was a German civil war. The principalities which made up Germany took up arms for or against the Habsburgs or, most commonly, both at different times during the war’s 30 years.
- The Thirty Years War was also, at least in part, a religious war among Catholics, Lutherans and Calvinists. Ferdinand II and, to a lesser degree, his primary ally Maximillian I represented the re-Catholicizing zeal of the Jesuit Counter-reformation, while Frederick V of the Palatinate represented the equally militant forces of Calvinism.
- The series of conflicts, military and political, which make up the Thirty Years War are highly complex.
- The Catholics and Protestants formed armed alliances to preserve their rights: the Catholic League under Maximilian I of Bavaria and the Protestant Union under Frederick V of the Palatinate.
- Meanwhile, in Bohemia, Moravia and Austria dissension between the Habsburgs had enabled the local elites to extort religious freedom from their rulers. The Habsburgs gradually began to chip away at these concessions.
- This phase of the Thirty Years War encompassed the years 1618 through 1621.