 One of the greatest distinguishing marks of the knightly class was the flying of coloured banners, to display power and to distinguish knights in battle and in tournaments.Knights are generally "armigerous" (bearing a coat of arms), and indeed they played an essential role in the development of heraldry.As heavier armour, including enlarged shields and enclosed helmets, developed in the Middle Ages, the need for marks of identification arose, and with coloured shields and surcoats, coat armoury was born.