Past studies conclude that a territorial integrity norm caused territorial conquest to decline sharply after 1945, virtually subsiding after 1975. However, using new and more comprehensive data on territorial conquest attempts, this study presents a revised history of conquest after 1945. Unlike attempts to conquer entire states, attempts to conquer parts of states remained far more common than previously recognized. More than conquest declined in frequency, its relationship with war evolved. Challengers attempting conquest before 1945 often initiated a war, then sought to occupy large territories. Today, challengers more often seize small regions, then attempt to avoid war. Adopting this strategy, the fait accompli, challengers increasingly came to target territories with characteristics that reduce the risk of provoking war—such as a low population and the absence of a defending military garrison—but challengers nonetheless take a calculated gamble. In part because seizures of smaller territories with such characteristics have not declined, the operative constraint appears to be against war-prone aggression, not territorial revision. The evolution of conquest is a symptom of war's decline, not its cause. Most of the evidence that the territorial integrity norm suppressed conquest or war withers under investigation with new data. Attempts to get away with seizing small pieces of territory are likely to be a defining element of the twenty-first-century international security landscape.

Contemporary studies of conflict have adopted approaches that minimize the importance of negotiation during war or treat it as a constant and mechanical activity. This is strongly related to the lack of systematic data that track and illustrate the complex nature of wartime diplomacy. I address these issues by creating and exploring a new daily-level data set of negotiations in all interstate wars from 1816 to the present. I find strong indications that post-1945 wars feature more frequent negotiations and that these negotiations are far less predictive of war termination. Evidence suggests that increased international pressures for peace and stability after World War II, especially emanating from nuclear weapons and international alliances, account for this trend. These original data and insights establish a dynamic research agenda that enables a more policy-relevant study of conflict management, highlights a historical angle to conflict resolution, and speaks to the utility of viewing diplomacy as an essential dimension to understanding war.

This article examines the relationship between third-party actors and the intentional targeting of non-combatants in interstate war. It argues that war participants kill fewer civilians in war when their expectation of third-party punishment is high. Combatants will anticipate a high likelihood of third-party sanctions when their alliance and trade networks are dominated by third parties that have ratified international treaties prohibiting the intentional targeting of non-combatants. The study hypothesizes that war combatants kill fewer civilians in war as the strength of ratifiers within their alliance and trade networks increases. Quantitative tests on a dataset of all interstate wars from 1900–2003 provide strong statistical and substantive support for this hypothesis.

The democratic peace literature has convincingly shown that democracies do not fight other democracies. Theoretical explanations of this empirical phenomenon often claim that the citizenry in democracies prefers peaceful resolution of interstate conflicts. Still, there is a dearth of studies exploring the public’s preferences and values directly. We seek to rectify this by investigating, in a novel way, the relationship between regime type and citizens’ bellicosity. A comprehensive multilevel research design is employed, with data spanning 72 countries over the period of 1981–2008. This enables us to test one of the theoretical mainstays of the democratic peace thesis, viz., that regime type helps shape individuals’ attitudes toward war-fighting. Our results lend special support to normative democratic peace theory: Citizens of democracies are significantly more pacifistic than citizens of non-democracies. This result upholds when we rigorously control for other relevant factors, including specific characteristics of individuals and rival theoretical explanations.