Martha of Denmark

Martha, Swedish Mrta , officially Margaret Eriksdatter of Denmark, was a Swedish Queen consort, spouse of King Birger of Sweden. She was regarded as a politically influential queen, and played a part in the Htuna games and the Nykping Banquet.

Mrta was born the daughter of King Eric V of Denmark and Agnes of Brandenburg and sister of King Eric VI. Her father was murdered in 1286, and her mother, who was made regent, remarried in 1293. Mrta was married to King Birger of Sweden in 1298. Two years before, her brother had been married to her husbands sister, Princess Ingeborg of Sweden, and her marriage was a part of a double alliance between Denmark and Sweden. The marriage was decided when she was a child the necessary dispensation from the Pope was obtained in 1284, and she spent a lot of her childhood in Sweden. Engaged to the Swedish crown prince as a child, she was largely brought up at the Swedish royal court by her future motherinlaw, the queen dowager Helwig of Holstein. She is confirmed to have lived in Sweden permanently from at least 1295.

Source: Wikipedia