Its ruler, the Prince of Dol Amroth, is subject to the sovereignty of Gondor. The principality's boundaries are not explicitly defined, though the Prince ruled Belfalas as a fief, as well as an area to the east on the map labelled Dor-en-Ernil ("The Land of the Prince"). Imrahil, Prince of Dol Amroth in "The Return of the King", was linked by marriage both to the Stewards of Gondor and to the Kings of Rohan. He was brother of Lady Finduilas and uncle to her sons Boromir and Faramir; a kinsman of Théoden; and the father of Éomer's wife Lothíriel. Imrahil played a major part in the defence of Minas Tirith; the swan-knights whom Imrahil led to Minas Tirith formed the largest contingent from the hinterland to the defence of the city. They marched under a banner "silver upon blue", bearing "a white ship like a swan upon blue water".