The chapter examines the development and changing nature of the laws and customs of war in Old Regime Europe. It focuses on land warfare, scrutinising the received idea that the waging of war in this age was characterised by a growing moderation and by the improvement of troops’ conduct and discipline. The chapter surveys the major principles and doctrines of the jus in bello and the use thereof made by European players. In doing so, it draws on state and military practice as well as scholarly – legal and military – literature. Subjects which are covered include the theoretical conceptualisation of the laws of war, status in war and neutrality – limited to its terrestrials aspects – the emergence of new legal constraints regarding the treatment of prisoners of war and civilians, siege warfare and use of weapons, the treatment of enemy possessions and occupation.

This chapter examines the development of the law governing warfare on land in Renaissance Europe. In this formative period, the law of war became a central feature of international relations and a distinct legal field. Wars of religion, the growth of the Ottoman Empire, dynastic disputes and the European expansion all contributed to an almost permanent state of warfare. Against this background, in the sixteenth and seventeenth centuries, several scholars contributed to the development of the law of war, responding to the political, religious and cultural turmoil of the Iron Century by elaborating different theories of such law. They derived concepts and principles from medieval theology, canon and civil law, as well as from history, literature and philosophy. The chapter relies on both primary and secondary sources drawing on state and military practice as well as scholarly – legal, historical and relevant military literature. It surveys the major principles of the ius in bello on land, the international law governing warfare including booty, siege warfare and the treatment of civilians and prisoners of war. Rather than describing the distinct contributions of several scholars to the early modern jus in bello – which could not do justice to the works of relevant scholars, especially in the light of recent outstanding works in the field – this chapter adopts an analytical approach focusing on key themes of the jus in bello, analysing and critically assessing the contributions of various scholars to the same.