Which two religious groups were involved in this war? MEG 101 Prerestoration

The Thirty Years' War was primarily fought between two religious groups: the Catholics and the Protestants. At the time, the Holy Roman Empire was a patchwork of smaller states and territories, many of which had different religious affiliations. The conflict began as a result of religious tensions between the Catholic authorities and the Protestant minority in Bohemia, which was then part of the empire. Over time, the conflict escalated as other Protestant territories joined the rebellion, and as Catholic states and other European powers intervened on behalf of the emperor and the Catholic cause. While the war had other political and economic factors at play, religion remained a central issue throughout the conflict.