A trend in modern warfare is to conduct war both conventionally and unconventionally. This modern era sets high demands on conventional forces to face the contemporary threat. Most of the modern conventional forces conduct war through maneuver warfare and uses the practice of combined arms to organize and fight, but is the method of combined arms still a valid method? This study examines Robert Leonhard’s theory of combined arms in the Yom Kippur war 1973 and during the American Thunder Runs in Baghdad 2003. The research question that this study is trying to answer is how the combined arms theory can explain the tactical success in the two cases. Previous studies about the theory explains how it could be understood, not how it is used. The theory encompasses three principles which is applied to the two cases to allow a structured analysis. The results show that both the Israelis and the Americans use the combined arms theory to achieve tactical success. What the analysis also shows is that the theory is not the only element that achieved success, but also technical advantage, moral and experience made an impact on the outcome of the cases.