An Open Order formation that is wider than it is deep (i.e., that has more models per rank than per file) or that is square (i.e., has the same number of models per file as per rank) is said to be in Combat Order. Such units are able to count a Rank Bonus in certain situations:

Rank Bonus

If a unit in Open Order formation is wide enough, it can claim a Rank Bonus of +1 for each rank behind the first, up to the maximum determined by its troop type:

• How many models a rank must contain to claim a Rank Bonus, as well as the maximum Rank Bonus a unit can claim, is determined by its troop type.

• Certain special rules may increase the Rank Bonus a unit can claim beyond the maximum normally allowed by its troop type.

Note that, as normal, this bonus can be claimed for an incomplete rear rank, as long as there are sufficient models in it.