 By the third century A.D. these Legions had been dispersed along the frontiers in frontier fortifications, and within the Empire as internal security troops.In the first case Rome's military might was disposed in a manner in which it had a concentration of force capable of offensive action; in the second case it could defend effectively but could only attack and counterattack with difficulty.As they are usually the smaller in number an appreciation of force concentration is especially important to guerrilla forces, who find it prudent initially to avoid confrontations with any large concentrations of government/occupying forces.