The world is rapidly becoming more urbanised and with key infrastructure being located inside or close to cities the probability of urban warfare in the next major conflict is very high. This thesis examines how the use of Alice Hills theory can explain success in urban warfare on the tactical level of war. The purpose of the thesis is to test the validity of Hills theory. To examine to what extent Hills’s theory can explain the success of the coalition forces during Operation Phantom Fury and the failure of Operation Vigilant Resolve, a theory testing case study is applied. The two cases have similar background variables, which allows for a structured comparison of the two cases. The analysis is based on Hills’s success factors in urban warfare. The results of the analysis reveal that Hills theory can explain the success of the coalition during Operation Phantom Fury and the failure of Operation Vigilant Resolve, thereby strengthening the validity of Hills theory. The results highlight the need to control the civilian population during urban combat. However, due to the difficulties of measuring success factors such as leadership and morale with the chosen method, the external validity of the results is negatively affected.