In the formation of the modern law of nations, peace treaties played a pivotal role. Many basic principles and rules that governed and still govern relations between states were introduced and elaborated in the great peace treaties from the Renaissance onwards. Nevertheless, until recently few scholars have studied these primary sources of the law of nations from a juridical perspective. In this edited collection, specialists from all over Europe, including legal and diplomatic historians, international lawyers and an International Relations theorist, analyse peace treaty practice from the late fifteenth century to the Peace of Versailles of 1919. Important emphasis is given to the doctrinal debate about peace treaties and the influence of older, Roman and medieval concepts on modern practices. This book goes back further in time beyond the epochal Peace of Treaties of Westphalia of 1648 and this broader perspective allows for a reassessment of the role of the sovereign state in the modern international legal order.