the virtual ruler of Sweden from 1248 until his death.

Before 1238 Birger married Ingeborg (d. 1254), the sister of King Erik Eriksson (1222–50), and was created jarl (earl) of Sweden in 1248. When Erik died, leaving no son, Birger obtained the election as king of his own son Valdemar, a minor for whom he acted as regent. He enlisted the support of the church against the magnates and the provincial assemblies and issued the first Swedish national laws developing the concept of the king's peace. He established closer links with Norway and Denmark, confirmed by marriage alliances: his daughter, Rikissa, in 1251 married the Norwegian heir apparent, and in 1261 he himself married Mechthild, widow of the Danish king Abel. He also extended Swedish influence to southern Finland and, by granting privileges, encouraged the Baltic city of Lübeck to increase its trade with Sweden. The claim that he founded Stockholm is in dispute, but under his regency Stockholm became the administrative centre of Sweden. He also made the country more civilized by enacting laws that protected the rights of women and doubled the penalties for crimes against the church and the king's councils.