The Forgotten Peace of Westphalia: How a 1648 Treaty Still Shapes Modern Borders

A 375-year-old agreement ended Europe's bloodiest religious wars and invented the sovereign state — but its principles are now bending under the weight of globalization and humanitarian intervention.

By the Jester Desk · September 1, 2026

In October 1648, after five years of negotiations involving 109 delegations, two treaties were signed in the Westphalian towns of Münster and Osnabrück. The Thirty Years' War had caused immense devastation across Central Europe, and the settlement that ended it did something unprecedented: it recognized the authority of rulers within defined territories and formalized limits on external interference in domestic religious and political affairs. The Peace of Westphalia is now remembered as the birth certificate of the modern nation-state system — even if, as some historians argue, that reputation was retroactively assigned centuries later.^[8][9]

What the Treaty Actually Did

The two treaties — the Treaty of Münster with France and the Treaty of Osnabrück with Sweden — collectively ended the Thirty Years' War and the Eighty Years' War, and brought peace to the Holy Roman Empire. The empire, which covered much of modern Germany, was a patchwork of around 1,800 distinct political units with overlapping claims of authority. Westphalia recognized these entities as independent sovereign states, granted Calvinism legal protection alongside Catholicism and Lutheranism, and established the principle that religious differences were not legitimate grounds for war. As one analysis put it, the treaties 'reoriented the European order toward territorial governance and mutual legal recognition as the basis for stability.'^[5][6][8][9]

The settlement also introduced concepts that became the backbone of international relations: sovereignty, mediation, and diplomacy. Before Westphalia, war was the primary tool for resolving conflicts; after it, negotiation emerged as a viable alternative. Sovereignty meant that a state had legitimate rights over its territory — declaring war, collecting taxes, and engaging in war-ending negotiations — and that no higher authority, neither the Pope nor the Holy Roman Emperor, could override those rights. As one scholar noted, the treaties 'transformed existing practices into mutually accepted legal commitments.'^[5][9]

Westphalia guaranteed the right to practice specific religions — a radical departure from the religious wars that had torn Europe apart for over a century.

The Westphalian System: A Convenient Myth?

The term 'Westphalian system' was popularized by international relations scholar Leo Gross in a 1948 article, which interpreted the peace as the beginning of a new epoch: the laicization of international law, the extension of its scope to include republican and monarchical states on equal footing, and the abandonment of a hierarchical society in favor of a system of sovereign states. For realist scholars, it became the starting point for a state-centered analysis of international politics. Yet as historian Stephen Krasner bluntly put it, the model 'had virtually nothing to do with the Peace of Westphalia' — the treaties themselves were more about settling specific territorial and religious disputes than establishing a grand theory of sovereignty.^[4][11]

The concept of Westphalian sovereignty — that each state has exclusive control over its territory and domestic affairs — reached its peak in the 19th and 20th centuries, enshrined in the United Nations Charter, which forbids intervention 'in matters which are essentially within the domestic jurisdiction of any state.' But recent scholarship has argued that the 1648 treaties had little to do with the principles of non-intervention and legal equality of states that are now attributed to them. The myth, however, has proven remarkably durable, shaping international legal and political thought for centuries.^[3][8]

Sovereignty Under Siege

In the post-Cold War era, the Westphalian ideal of non-interference has been repeatedly challenged. After the Cold War ended, the United States and Western Europe began discussing a 'post-Westphalian order' in which countries could intervene in others' affairs to prevent human rights abuses. As one analysis noted, 'The Westphalian concept of sovereignty has been challenged by military intervention in recent international conflicts.'^[3]

Yet the principle still holds enormous power. Citizens may demand military intervention when they see moral wrongs abroad, but 'in virtually all cases, the principle of sovereignty prevents it.'^[12]

Borders, Separatists, and the Double-Edged Legacy

The Westphalian principle of territorial integrity — that borders should be respected — is both invoked and rejected by separatist movements worldwide. As one source put it, 'Current border disputes or separatist movements invoke or reject Westphalian principles.'^[2]

The principle of uti possidetis — that borders inherited at independence should be maintained — has locked in unstable status quos across Africa and the Balkans, contributing to civil conflicts. The American Academy of Arts and Sciences notes that applying Westphalian principles to post-1945 states 'has contributed to civil conflicts,' because these principles presuppose a hierarchical government within a territory, which many new states lacked.^[14]

International Organizations: Reinforcing and Undermining

Modern international organizations are a paradox: they reinforce the Westphalian system by recognizing states as the primary actors, yet they undermine it by pooling sovereignty. The United Nations is built on Westphalian principles — its charter enshrines the sovereignty of member states — but its Security Council can authorize interventions that violate that sovereignty. The European Union goes further, creating a supranational legal order that supersedes national laws, a clear departure from Westphalian exclusivity. As one analysis concluded, 'Modern international organizations and agreements both reinforce and undermine the Westphalian system.'^[2][3]

The rise of non-governmental actors, from multinational corporations to international criminal tribunals, further erodes the state's monopoly on authority. These developments are often analyzed as signs of the 'decline' of the Westphalian system, yet the state remains the primary unit of international politics.^[4]

The Criticisms: Globalization, Human Rights, and Intervention

Critics of the Westphalian model argue that it is ill-equipped to handle the challenges of globalization, human rights, and intervention. The principle of non-interference has been used to shield authoritarian regimes from accountability, while the Westphalian emphasis on state sovereignty undermines efforts to address global issues like climate change, migration, and pandemics, which transcend borders. As one source put it, 'Criticisms of the Westphalian model arise in the context of globalization, human rights, and intervention.'^[2][3]

The Westphalian system also fails to address the reality of weak or failed states, where sovereignty is nominal but not effective. The principle of sovereign equality — that every state, no matter how large or small, has an equal right to sovereignty — is a legal fiction when some states cannot control their own territory. This has led to calls for a 'post-Westphalian' order that recognizes shared responsibility for human security.^[3]

A Legacy That Endures

Whatever the historical accuracy of the 'Westphalian moment,' the ideas associated with it have profoundly shaped international law and politics. The peace settlement of 1648 may not have invented sovereignty from scratch, but it consolidated existing practices into legal commitments that have endured for centuries. As one scholar noted, 'The significance of the Westphalian agreements lies instead in their consolidating function.'^[9]

Today, as the world grapples with the limits of sovereignty in an interconnected age, the 375-year-old treaty remains a reference point — both as a foundation and as a foil. The debate over Westphalia is ultimately a debate about what kind of international order we want. The peace that ended the Thirty Years' War may have been forgotten by many, but its principles are still shaping the borders and battles of the 21st century.^[8][9]

Reported with AI assistance using internet sources.