The response to many on-going or emerging conflicts since the beginning of the 21st century has been different forms of multinational complex peace operations. Civil-military relations are a commonly studied field that traditionally has its focus on nations. This study intends, in the context of organisations, to test the correlation between a civil-military approach and outcome in complex peace operations. A hypothesis has been deduced from researcher Robert Egnell’s theory on complex peace operations, that states that: UN peace operations with an integrated civil-military approach are more successful in achieving their goals than peace operations with a divided approach. This hypothesis is tested by comparing the outcome of two different complex peace operations with diverse approaches to civil-military relations. The cases were selected by a comparative design and thereafter thoroughly analysed in relation to their respective goals. The analysis revealed that the integrated UN approach in Sierra Leone through UNAMSIL was far more successful in achieving its goals, than the divided UN approach applied in Afghanistan via UNAMA and ISAF. In regard to the result, the hypothesis was not falsified which indicates that there is a correlation between a civil-military approach and outcome in organizations. More specifically, an integrated approach to complex peace operations is more successful in achieving its goals than a divided one.