 The duchy was regularly contested by the French and the Holy Roman Empire, which brought about repeated military operations.Internally, from the 12th to the 15th century, there was the usual party strife between the Guelphs, who generally supported the political and religious policies of the Papacy; and the Ghibellines, who generally supported the Emperors.As Kings of Italy, the emperors were feudal overlords of Lombardy.