The increased probability that future battles will take place in cities can leave military organizations unprepared for future conflicts. Urban warfare requires a different tactical approach than battles in other terrain due to its unique complexity. Previous research on urban warfare tends to agree that combined arms contribute to urban tactical success but lacks on explanations for how it carries into effect inside cities.   This study will examine how combined arms can lead to tactical victory, in a theory-testing approach, by analyzing the U.S assaults on Aachen in 1944 and Fallujah in 2004 during Operation Phantom Fury. Since the Swedish Armed Forces can be considered tactically influenced by Robert Leonhards theory on combined arms, the purpose of this study is to examine the theory’s ability to explain tactical success in urban terrain. The results show that an attacking combined arms force with superior firepower can put the defending enemy in a dilemma. However, the dilemma creates unfavorable conditions for the Alcyoneus principle of the theory to explain why the attacking forces succeeded.