The thirty years' war brought an end to the holy roman empire. ended the monarchy in england. unified germany. pitted spain against its dutch provinces.

The thirty years' war brought an end to the Holy Roman Empire. 
The thirty Years' war is a series of wars fought by various reasons, including, dynastic, territorial, and commercial rivalries. Its destructive campaigns and battles occurred over most of Europe. The war originated with dual crises at the continent's center; one in the Rhineland and the other in Bohemia, both part of the Holy Roman empire.

Because he proposed that all the treaties should be made through the league of nations.