What Was the Peace of Westphalia, and Why Does It Matter?

The Peace of Westphalia is the pair of treaties signed in October 1648 at Münster and Osnabrück that ended the Thirty Years’ War (1618–1648) in the Holy Roman Empire and closed the Eighty Years’ War between Spain and the Dutch. It fixed the religious settlement of the Empire, confirmed the independence of the Dutch Republic and the Swiss Confederacy, and handed territory to France and Sweden. It matters partly for what it settled and partly for the idea later attached to it: that 1648 founded a world of sovereign states — a claim many historians now call a myth.

What was actually signed

“Westphalia” is two documents, not one: the Treaty of Osnabrück, between the Emperor Ferdinand III with the Empire on one side and Sweden with its allies on the other, and the Treaty of Münster, between the Emperor and France. Both were signed in October 1648 after negotiations that ran for years in the two Westphalian towns. Roughly 109 delegations took part, representing European crowns, Imperial estates and interest groups — a scale of diplomacy Europe had not seen before.

Separately, at Münster in January 1648, Spain had already recognised the independence of the Dutch Republic, ending the Eighty Years’ War that had begun in the 1560s. That is why the Peace is usually said to have ended two wars.

What it settled

Inside the Empire, the treaties reworked the religious peace of Augsburg (1555). Calvinism gained legal recognition alongside Lutheranism and Catholicism, and 1 January 1624 was fixed as the “normative year” that decided which confession a territory would keep — a device meant to stop the seizures of church land that had helped start the war.

Territorially, France kept the bishoprics of Metz, Toul and Verdun and gained rights in Alsace; Sweden received Western Pomerania, Wismar and the secularised bishoprics of Bremen and Verden; Brandenburg took Farther Pomerania and several bishoprics. The Dutch Republic and the Swiss Confederacy were confirmed as independent of the Empire.

The “Westphalian sovereignty” argument

In twentieth-century political science, 1648 became shorthand for the birth of the modern state system: equal sovereign states, non-interference, no authority above the prince. Historians who read the treaties find little of this in the text. Andreas Osiander’s much-cited 2001 article called the idea “the Westphalian myth,” arguing that the sovereignty doctrine grew in the nineteenth and twentieth centuries and was read back into 1648; Derek Croxton’s Westphalia: The Last Christian Peace (2013) makes the same case in book length. The treaties did not abolish the Empire, did not free German princes from the Emperor, and say nothing about a general principle of state sovereignty.

The fairer claim is narrower: Westphalia showed that a continental war could be ended by a general congress in which many states negotiated at once, and it produced a religious settlement in Germany that broadly held.

What most scholars accept, and what stays contested

Accepted: Two treaties, Münster and Osnabrück, signed in October 1648; they ended the Thirty Years’ War (1618–1648); Spain recognised Dutch independence at Münster in January 1648; Calvinism was legally recognised in the Empire and 1624 set as the normative year; the Swiss Confederacy and the Dutch Republic were confirmed as independent.
Mainstream: Westphalia was a religious and territorial settlement for the Holy Roman Empire and its neighbours, negotiated by an unprecedented congress, whose direct effects were German; the “birth of the sovereign state” reading is a later construction.
Contested: How much of the modern sovereignty idea, if any, can be traced to 1648; whether the settlement weakened the Empire decisively or stabilised it; and how far the Peace ended, rather than paused, confessional conflict in Germany.

Frequently asked questions

When was the Peace of Westphalia signed?

The treaties of Osnabrück and Münster were signed in October 1648, after negotiations that had run since the mid-1640s. The separate Spanish–Dutch peace at Münster was concluded in January 1648.

Which wars did the Peace of Westphalia end?

The Thirty Years’ War (1618–1648) in the Holy Roman Empire, and, through the Spanish–Dutch treaty at Münster, the Eighty Years’ War between Spain and the Dutch Republic.

Did Westphalia create the modern system of sovereign states?

Most historians of the treaties say no. The text contains no general principle of state sovereignty; the Empire and the Emperor’s authority survived. The “Westphalian system” is largely a twentieth-century label, which Andreas Osiander (2001) called the Westphalian myth.

What did France and Sweden gain?

France kept Metz, Toul and Verdun and gained rights in Alsace; Sweden gained Western Pomerania, Wismar and the former bishoprics of Bremen and Verden, giving it a voice in the Imperial Diet.

Sources and further reading

Peter H. Wilson, Europe’s Tragedy: A New History of the Thirty Years War (Allen Lane, 2009)
Derek Croxton, Westphalia: The Last Christian Peace (Palgrave Macmillan, 2013)
Andreas Osiander, “Sovereignty, International Relations, and the Westphalian Myth,” International Organization 55, no. 2 (2001)
Wikipedia, “Peace of Westphalia” (checked 3 September 2026)