A European war of 1618–48 which broke out between the Catholic Holy Roman emperor and some of his German Protestant states and developed into a struggle for continental hegemony with France, Sweden, Spain, and the Holy Roman Empire as the major protagonists. It was ended by the Treaty of Westphalia.
Definition of Thirty Years War in US English:
Thirty Years War
proper noun
A European war of 1618–48 which broke out between the Catholic Holy Roman emperor and some of his German Protestant states and developed into a struggle for continental hegemony with France, Sweden, Spain, and the Holy Roman Empire as the major protagonists. It was ended by the Treaty of Westphalia.