A unit arrayed in serried ranks is said to be in a 'Close Order' formation. A unit in Close Order consists of two or more models that are arranged in base contact with each other, edge-to-edge and front corner to front corner, as shown in Fig 100.1.

All models in such a unit must face the same direction. In addition, the models must be arranged into a formation that consists of one or more horizontal rows called ranks, and a number of vertical rows called files (from this formation comes the term 'rank and file').

As far as possible, there must be the same number of models in each rank. Where this is not possible, it must be the rear rank that has fewer models. Once formed into a unit, the models move and fight as a single entity for the entire battle.