Guarantee and Intervention: the Assessment of the Peace of Westphalia in International Law and Politics by Authors of Natural Law and of Public Law, c. 1650–1806

The Peace of Westphalia is simultaneously one of the most thoroughly researched, and one of the most misunderstood peace settlements of early modern history, albeit not by the same people. The fact that this paradox has persisted in the last two decades, when detailed historical research into the treaties of Münster (Instrumentum Pacis Monasteriensis, ipm) and Osnabrück (Instrumentum Pacis Osnabrugensis, ipo)1 and their implications has been booming, is indicative of the tenacity of the myth surrounding Westphalia.2 Broadly, the misperception of Westphalia has two dimensions, the international – according to which the Peace inaugurated a new international ‘Westphalian system’ of equal, sovereign states which do not intervene in each other’s domestic affairs3 – and the internalconstitutional, which alleges that the treaties granted the princely territories (Imperial Estates) of the Holy Roman Empire