"Although most disputes between groups of people are settled peacefully, sometimes disputes result in war. This lecture uses historical examples to illustrate how the ability to negotiate a credible peaceful settlement of a dispute between sovereign states, typically a dispute over the control of territory or natural resources, depends on the divisibility of the outcome of the dispute, on the effectiveness of the fortifications and counterattacks with which an attacker would expect to have to contend, and on the permanence of the outcome of a potential war. The lecture also contrasts the possibilities for avoiding wars between sovereign states with the possibilities for avoiding civil wars"--National Bureau of Economic Research web site.