War is a defining and enduring element in the study of international history. But how it has been conceived and analysed by international historians has evolved. Whereas an earlier generation of international (or diplomatic) historians placed war, or at least how nation-states navigated the prospect of war, at the centre of their disciplinary identity, they rarely explicitly considered war as a concept—what distinguishes it from other forms of political violence, and how its form and content change over time. These earlier international historians assumed that they knew what war was when they saw it, and so did not feel the need to question war itself as a category of analysis. More recent historiographical trends, however, have seen exactly that type of questioning. This paper seeks to map some of those recent trends and put them into conversation with each other. In doing so, it will consider war from three different vantage points: law, geography, and technology.
Historians have come to appreciate that it is often law (and the politics of law) that produces the taxonomy of political violence by which we comprehend (and then either legitimise or condemn) certain actions in international life. We know what war is by way of law, and a “legal turn” has been at the heart of recent efforts to understand war and its place in the international imaginary. Law determines when particular acts of violence amount to war (see, e.g., Mary Dudziak, War·Time), where those acts of violence can occur (James Q. Whitman, The Verdict of Battle), who can wage war, both at the level of states and individuals (David Armitage, Civil Wars; Maartje Abbenhuis, An Age of Neutrals; John Fabian Witt, Lincoln’s Code; Sibylle Scheipers, Unlawful Combatants: A Genealogy of the Irregular Fighter), and how it can be waged (Isabel Hull, A Scrap of Paper).
Tracing the shifting legal outlines of war helps, in turn, to appreciate the changing spatial and technological foundations of war. The reality of a strictly-demarcated battlefield may have declined from the nineteenth century, but the idea of a “battle” as a discrete, delineated event persisted for some time, reinforced by forms of geographic knowledge and tools (maps) that produced a close association between ideas of political authority (including victory) and territory. New forms of geographic knowledge (e.g., GPS) emerged in the twentieth century, however, that allowed for a shift in understanding space in terms of an area to understanding it as a collection of co-ordinates or points, with important consequences for how—and where—war was waged (William Rankin, After the Map). Technological developments, in particular the rise of precision-guided munitions, further enabled the ascendancy of these new forms of geographic and legal knowledge.
We often now talk of war as “endless” or “everywhere”. By bringing together the work of historians in several subfields, this paper seeks a deeper and more rigorous understanding of how war—and its enduring place in defining the international sphere—has changed.