Since the end of the Second World War, civil conflicts emerged as one of the major threats to security not only in their respective regions but also for the whole world, especially for powerful states. With the demise of the Soviet Union, the number of new intrastate wars decreased, but the existing wars increased in duration. This thesis examines this phenomenon from Immanuel Wallerstein’s world-systems analysis perspective by arguing that the flow of capital from the periphery states to the core countries that takes place during the conflict increases the duration of the respective civil war. The main objective is to shed light on the causes of the entrenched civil warfare in Sub-Saharan Africa. This research uses theory building case study method, looking at civil wars in Angola, the Democratic Republic of Congo and Sierra Leone. The evidence presented in the cases suggests that the powerful core states and firms located in these countries affect the duration of civil conflicts through engaging in activities aimed at increasing their capital. These states carry out international trade in illegally extracted natural resources, most notably ‘blood diamonds’, which provides funding for the warring factions. In addition, private security firms or mercenaries drain both money and resources from war-torn states under the covert support from the core states. This thesis contributes to the theoretical framework of Wallerstein’s world-systems analysis and to the literature on civil conflicts