Explaining the Duration of Counterinsurgency Campaigns * Patrick B. Johnston † Brian R. Urlacher ‡ April 5 2011 Abstract Why are some counterinsurgency campaigns resolved quickly while others last for decades? Numerous scholars have addressed this question in the context of civil war. These studies suggest that commitment problems, a county’s level of economic development, and third-party intervention explain variations in the du- ration of civil wars. We test the hypotheses developed in the civil war literature, using a new dataset of counterinsurgency campaigns between 1800-2000. Pre- vious literature on civil war duration pooled together “regular” and “irregular” civil wars. By isolating irregular wars that took the form of classic guerrilla insur- gencies, the results reveal the extent to which insights from the civil war duration literature are applicable to campaigns of insurgency and counterinsurgency. We find that the greatest differences in duration can be attributed to historical eras. Also, we find that the effect of several variables changes over time. * An earlier version of this paper was presented at the 2010 Annual Meeting of the Midwest Political Science Association, Chicago, IL. † Research Fellow, Belfer Center for Science and International Affairs, John F. Kennedy School of Govern- ment, Harvard University and Post-Doctoral Scholar, Department of Political Science, Stanford University. Email: Patrick Johnston@hks.harvard.edu. Mailing Address: 79 John F. Kennedy Street, Mailbox 134, Cambridge, MA 02138. ‡ Assistant Professor, Department of Political Science & Public Administration, University of North Dakota. Email: brian.urlacher@business.und.edu. Mailing Address: 265F Gamble Hall, University of North Dakota, Grand Forks, ND. 1