By 1648, Europe was ravaged in the religious civil war known as the Thirty Years War which initially pitted the Catholics against the Protestants, but eventually devolved into a power struggle between the French Bourbon and the Austrian/Spanish Hapsburg dynasties. Since 1618, foraging armies crisscrossed Poland, the German principalities, and the southern Netherlands, massacring those of another faith and looting their towns and cities. The Seven United Dutch provinces were for all intents and purposes independent as the Dutch Republic, but had been in revolt since 1568 against the Hapsburgs of Spain. To the Dutch, the Thirty Years War was just another phase of the Eighty Years War. On 30 January, 1648, as part of the ongoing negotiations to end all of the destructive conflicts in Europe, Dutch and Spanish officials signed the Treaty of Munster which formally recognized the Dutch Republic. Though fighting would continue for three more months until the treaty was approved by the Bourbon and Hapsburg monarchs.
The Treaty of Munster was the first of a series of treaties over the course of 1648 known as the Peace of Westphalia that ended the Thirty Years War. The Peace of Westphalia elevated and established the sovereign state over the sovereign dynasties (Spain and France as opposed to Bourbon and Hapsburg) which would cement a principle of non-intervention in another state’s affairs, particularly religious affairs. It also established the legal precedent of state equality in international law, no matter how large or small the size of the states, which is the foundation of our modern international system. In doing so, the Peace also effectively ended the Holy Roman Empire as a major political entity. Most importantly though, the Peace of Westphalia ended intra-faith warfare among Christians, and they would no longer go to war strictly for theological reasons. Finally, the Treaty of Munster gave us the Netherlands.