A skirmish is an encounter between small groups fighting in loose or dispersed formation rather than formal ranks and files. Such an encounter might take place over a broad area of woodland or a group of buildings, where skirmishers can spread out to infiltrate the wood or occupy buildings. In a battle, only specified troops are allowed to skirmish, as indicated in their Army book. However, any units can adopt a skirmish formation in order to enter buildings, as described in the Buildings section.