States and other actors choose their methods of warfare, and the choice is rarely arbitrary. The choices reflect an actor's resources, the current stakes and risks, and strategic considerations. Stephen Biddle (2021) argues that non-state actors – such as guerrillas, militias, and warlords – make rational choices along a spectrum from Fabian to Napoleonic methods of warfare, driven more by operational conditions than by ideology or tradition. Biddle's theory explains the military behavior of non-state actors and their choices of warfare methods. This study tests the theory's applicability by applying it to Finland during the Winter War of 1939-1940 – a case that lies outside Biddle's original focus – to examine whether the theory can also explain method choices of state actors. The thesis result is that it can partly explain the outcome and the theory is therefore usable in this specific case and hopefully could be in other conflicts and cases of interstate wars in the future.