 DBM evolved from the earlier De Bellis Antiquitatis (DBA) rule set, adapted to play larger games with more figures, comparable in size to games played using the then popular 7th Edition WRG Ancient rules.DBM expanded on DBA's definition troop types by function and level of training - defining troops as regular bladesmen rather than Roman legionaries for example - by adding grades for each and rating them as Regular or Irregular.Grades such as Superior, Ordinary and Inferior troops are designed to reflect relative efficiency compared to contemporary opponents, and reflect morale, equipment, mounts, and training.