Troops move and fight in a tight formation of one or more ranks. Such a formation is often referred to by an appropriate title such as a regiment or, in the case of cavalry, a squadron, or it can simply be called by the cover-all term 'unit'.

While a unit moves it must maintain its formation, which means that models are not free to wander off on their own. The formation can move straight forward as a body perfectly easily, but if it wishes to change direction then it must make a manoeuvre.

There are three specific manoeuvres that enable a unit to turn about or rearrange its ranks: wheel, turn and change formation. In addition, there is a fourth special manoeuvre called reforming.