 Their main tactical units were the Numerus (Also called at times Arithmos or Banda) of 300-400 men.The equivalent to the old Roman Cohort or the modern Battalion, the Numeri were usually formed in lines 8 to 10 ranks deep, making them almost a mounted Phalanx.The Byzantines recognized that this formation was less flexible for cavalry than infantry but found the trade off to be acceptable in exchange for the greater physical and psychological advantages offered by depth.