| Military intervention has been undertaken numerous times since the end of World War II. Such involvement has most commonly taken the form of arms provisions to groups, but has, as in the case of Vietnam, Afghanistan, and Somalia, taken the form of large-scale, combat-force deployments. The five permanent members of the United Nations Security Council have undertaken a number of interventions, both unilaterally and with groups such as the UN. Yet these interventions are more likely to fail to achieve their goals than to succeed.; This study examines eighty-nine civil wars to understand what factors are likely to lead to intervention by these five states and whether those factors are likely to lead to success, failure, or stalemate. Fourteen variables, reflecting national interests and military concerns, were studied. These variables were analyzed using logistical regression to understand their effects.; The findings suggest that both military concerns and national interest factors play a role in predicting when intervention will take place, but have little significant effect on the probability that such interventions will succeed in achieving the goals. More interestingly, unilateral interventions undertaken to aid governments are more successful when undertaken late in the war and at lower levels of involvement. Interventions to aid opposition groups, however, are more successful when undertaken early in the war and at high levels. Supplemented by information from six case studies of civil wars in which one or more great powers intervened, it is argued that legitimacy, defined here as the belief that a faction has the right to rule, is key in civil wars. As the two (or more) factions fight over the same population, winning that population over is key to victory. While military force is never of negligible importance, too much force, particularly from an outside power, can serve to de-legitimize the very group the intervening actor is seeking to aid. A four-part model is created, examining the roles of insurgents, governments and intervening actors throughout the life of a civil war. |
