Background Swedish wildfires are handled by multipurpose municipal rescue services, raising questions about how non-specialist incident commanders (ICs) perceive and interpret wildfire behaviour. Aims Elucidating ICs’ interpretations of fire behaviour, fuel complexes, weather, landscape structure and the role of these in tactical decisions. Methods We exposed Swedish ICs to questionnaires and tabletop exercises for different standardised fire scenarios. Key results Despite minimal formal wildfire training, ICs showed reasonable consensus in rating of fuels, fire behaviour, hose-lay production rates, etc. Tactics were to access the fire from the nearest road with hose-line laid from the engine and water ferried on trucks. In a scenario where initial attack failed, they typically fell back to roads, without burning off. This indicates a fundamental flaw in tactics employed for high-intensity fires, which easily breach forestry roads, and invite outflanking. Conclusions The IC wildfire knowledge is built on personal and group experience rather than formal education. We found reasonable competence, despite the organisations being designed primarily for other purposes. However, tactical understanding of complex, large incidents was poor. IC training should emphasise potential hazards of such incidents to enhance group competence despite their low frequency. Implications Standardised tabletop exercises can provide insight into decision-making of ICs that is otherwise hidden.