 In Europe, during the High Middle Ages, flags came to be used primarily as a heraldic device in battle, allowing more easily to identify a knight than only from the heraldic device painted on the shield.Already during the high medieval period, and increasingly during the Late Middle Ages, city states and communes such as those of the Old Swiss Confederacy also began to use flags as field signs.Regimental flags for individual units became commonplace during the Early Modern period.