The dukes maintained relations with foreign monarchs, especially the king of England: Emma, sister of Richard II married King Ethelred II of England. They appointed family members to positions as counts and viscounts, which came about around the year 1000. They held on to some territory in Scandinavia and the right to enter those lands by sea. The Norman dukes also ensured that their vassal lords did not get too powerful, lest they become a threat to the ducal authority. The Norman dukes thus had more authority over their own domains than other territorial princes in northern France. Their wealth thus enabled them to give large tracts of land to the abbeys and to ensure the loyalty of their vassals with gifts of fiefdoms. William's conquest of England opened up more land to the dukes, allowing them to continue these practices whilst preserving sufficient land holdings to serve as their powerbase.