The major religious conflict that took place in Europe from 1618 to 1648 was the Thirty Years' War. This devastating war began as a conflict between Protestant and Catholic states within the Holy Roman Empire but quickly escalated into a broader struggle involving many European powers. It resulted in widespread destruction and significant loss of life, altering the political and religious landscape of Europe. The war concluded with the Peace of Westphalia, which established principles of state sovereignty and religious tolerance, effectively reshaping national borders and reducing the power of the Catholic Church in European affairs.