The Thirty Years' War.

The Thirty Years' War is the catch‐all term used to describe the wars that engulfed parts of Europe and beyond between 1618 and 1648. The core of the war was fought over various constitutional and, to a degree, religious, issues in the Holy Roman Empire, though it was arguably not a “German” war alone. It involved a variety of powers from northern Europe to the Mediterranean, and their satellite conflicts also. Nor was this just a military conflict. It was as much a complex, and constant, series of diplomatic maneuvers and negotiations, leading ultimately to the Westphalian Peace of 1648, often (if not entirely correctly) seen as a pivotal settlement in the history of international relations