The participation of PSMCs in security governance has spurred a vivid debate on the consequences of their involvement in counterinsurgency operations, their effects on civil-military relations or their impact on military effectiveness. In contrast, much less attention has been focused on the repercussions of PMSC involvement in civil wars. The findings, so far, are few and quite diverse. Deborah Avant argues that the likelihood of conflict increases as the control over violence is dispersed among more actors. Likewise, Sarah Percy has argued that PMSCs have negative repercussions as they prolonged war. Herbert Howe, in contrast, considered Executive Outcomes engagement in Sierra Leone to have shortened the civil war. The paper seeks to contribute to this debate by systematically exploring the impact of PMSC participation on the onset, duration and intensity of civil wars. It sets out by conducting a very brief co-variance analysis based on the PRIO conflict dataset and data on PSC involvement in conflicts. The aim is to explore broad trends and the strength of the effect of PMSC involvement. Against the backdrop of this analysis, the article will then describe the mechanisms that transmit the effects of PMSC involvement on civil war. For instance, some authors have argued that PMSCs are prone to human rights violations, which suggests an increase in intensity (Human Rights First). Others have claimed that PMSCs provide additional military capability to states, which should affect the onset or the duration of war (Christopher Kinsey). In order to explore these mechanisms, four or five in-depth case studies will be conducted.
