War-Making and Restraint by Law: The Formative Years, 1864-1914

Recent historical research in international and transnational history claims that a new international order developed in the later nineteenth century. Often framing it as an inquiry into the making of the contemporary global age, historians have pointed to the emergence of a “new internationalism” of sentiments, institutions, and intergovernmental agreements. On an independent track, legal scholars have pinpointed significant changes in the sphere of international law, starting in the mid nineteenth century. As part of the remarkable growth in state interdependence, formal canons of law began to govern many aspects of interstate relations, from commerce and trade to copyright, transportation, and war. Spearheading this shift was the movement to codify the laws of war, which had long been regulated by customary norms and ad hoc bilateral agreements. First written as multilateral treaties and agreements around the middle of the century, these new instruments became the hallmark of modern international law. In the words of Arthur Nussbaum, an early but influential legal historian, the shift to written multilateral law inaugurated a “new era” in legal history, although it remained in its “early stages” on the eve of World War I.