The Thirty Years' War (1618-1648) was a major conflict in Europe, primarily fought in the Holy Roman Empire. It began as a struggle between Catholic and Protestant states but evolved into a broader political war involving many European powers, including France, Sweden, and Spain. The war caused widespread destruction and significant loss of life. The conflict ended with the Peace of Westphalia, which established a new political order in Europe based on the principles of state sovereignty and religious tolerance. This treaty marked a turning point in European history, shaping the modern nation-state system and reducing the influence of religion in political affairs.