Modern military doctrines, including Sweden’s, emphasize the necessity of applying the art of combined arms, presuming that it will result in victory on the battlefield. However, the concept of combined arms is not clearly described in such doctrines. Not even researchers on the subject have a shared understanding of what combined arms is and how the concept should be applied to achieve success. There is hence a need for a thorough and up-to-date theory of combined arms. This study examines whether Robert Leonhard’s 1990s theory of combined arms could offer such a framework, applying it to the Russia–Ukraine war, specifically the two Ukrainian offensives in Kharkiv and Donetsk-Zaporizhzhia of which only one was successful. The research question of this study is whether Leonhard’s theory of combined arms can explain the diverging outcome of the cases.
The study suggests that the Ukrainian forces implemented combined arms in Leonhard’s meaning in the successful Kharkiv offensive. Indeed, all three of Leonhard’s core principles were implemented to some extent in Kharkiv, while not more than two of the principles were relied upon in the Donetsk-Zaporizhzhia offensive.
The explanatory power of Leonhard’s theory was strengthened by this study, and the theory could be a contender to fill the need for the up-to-date framework of combined arms.