When Emperor Justinian II in 692 attempted to have Pope Sergius I forcibly conveyed to Constantinople, (as had been Pope Martin I), to extract from him his assent to the canons of the Trullan Council, convoked by the emperor, the militia of Ravenna and of the Duchy of the Pentapolis lying immediately to the south assembled, marched into Rome, and compelled the departure of the emperor's plenipotentiary. In AD 715 the papal chair, which had last been occupied by seven eastern popes, was filled by a westerner, Pope Gregory II, who was destined to oppose Leo III the Isaurian in the Iconoclastic conflict.