Tying the story of the development of the laws of war to key structural and cultural changes occurring within the societies that develop and adopt such behavioural proscriptions, this history, the second of two volumes, examines the emergence of international law and legal orders whereby warfare and its conduct begin moving out of the realm of cultural norms and into a quasi-legal space, where specific principles of international law in general, and laws of war in particular, become more precisely articulated, formalized, and codified. Examining the evolution and multiplication of laws constraining how warfare is waged from the founding of the United Nations and the formalized creation of the Geneva Conventions to the contemporary era, the utilization of ad hoc tribunals in the post-war period, and the establishment of the International Criminal Court in the early 21st century, Mullins provides a cogent understanding of how this historical moment developed and what paths potential lie ahead.