Treaty of Lödöse The Treaty of Lödöse ( , ) was a peace treaty between the Swedish king Eric XI and the Norwegian king Haakon IV . The treaty was negotiated between King Haakon and the Jarl of Sweden , Birger Magnusson , in the town of Lödöse , during the summer of 1249 . The main purpose of the treaty was to prevent mutual hostility from escalating into war . Some factions of the Swedish nobility wanted to attack Norway in retribution for a raid by King Haakon , which had targeted Norwegian rebels in the Swedish province of Värmland 24 years earlier . In Lödöse , the two parties sworn that from then on fraternity and peace should prevail between the two kingdoms and that neither of the two would support or provide a haven for enemies of the other . It was also decided that Birger ' s daughter Rikissa , would marry the son of Haakon , Haakon the Young . Background . The Nordic royal families were closely related during the Middle Ages , and the formation of different alliances constantly threatened stability in Scandinavia . All three kingdoms sought to prevent the other two from dominating the region . Domestic politics in Norway , Denmark , and Sweden was above all shaped by the struggle between different clans for possession of the throne . In Sweden , the House of Eric ( supported by Denmark ) and the House of Sverker ( supported by Norway ) had been contesting for power since the murder of King Sverker the Elder in 1156 . Norway was at the time plagued by a prolonged civil war . Several pretenders to the throne were challenging King Haakon IV . Forces supporting the pretender Sigurd Ribbung used the Swedish province of Värmland as a safe haven for operations into Norway . Emissaries of the Norwegian king complained to the lawspeaker of Värmland and the Swedish king several times , but to no avail . Since the Swedes took no action against Ribbung , King Haakon led his army into Värmland during the winter of 1225 . There he plundered the region in an attempt to quell Ribbung ' s rebellion . Haakon ' s incursion angered the Swedes , but because of their internal conflicts they were unable to retaliate . In 1229 , the thirteen - year - old King Eric XI of Sweden was ousted from the throne by one of the members of his privy council , Canute II . After his supporters were overpowered at the Battle of Olustra in Södermanland , Eric was forced to flee to Denmark . Following the battle , Canute declared himself King of Sweden . His reign was marked by unrest and violence . In the year 1234 , Eric returned to Sweden and re - conquered the throne . The treaty . After Eric was reinstated as king , some factions of the Swedish nobility advocated war with Norway . They wanted retribution for the Norwegian plundering of Värmland . According to the Norwegian saga " Sverris saga " , the future jarl Birger Magnusson , were among those in favour of war ; however , at the time , the " de facto " ruler of Sweden Jarl Ulf Fase and his supporters were against attacking Norway . To prevent mutual hostility from escalating into war , Haakon IV of Norway sent an envoy to Sweden to conciliate . The Swedes agreed to talk , and a delegation led by Birger was sent to Kungahälla in Norway . Negotiations were held in the spring of 1241 , however , no agreement was reached . In 1247 , Sweden re - approached Norway , and a meeting between the two Kings was scheduled in the town of Lödöse in the province Västergötland for the summer of 1248 . Lödöse was chosen as the meeting place because it was situated in the nearest Swedish province that could be reached by sea from Norway . The following year , Eric traveled to Lödöse at the scheduled time , but Haakon was delayed . Eric waited for Haakon , but was forced to leave when his supplies started running low . A new meeting , at the same place , was scheduled for the next year . In the summer of 1249 , Eric returned to Lödöse , together with his brother - in - law Birger , who had by then become Jarl of Sweden . When the Swedes saw Haakon approaching Lödöse from the sea with a large fleet , they became scared and fled . Haakon sent a messenger bidding the Swedish king to come back and negotiate ; however , the king was already in Östergötland and did not want to return . Instead , Birger Jarl , the " de facto " ruler , traveled back to Lödöse to negotiate with the Norwegian king . After negotiations , Birger Jarl and King Haakon came to an agreement and sworn that from then onward , fraternity and peace would prevail between the two kingdoms and that neither of the two would support or provide safe haven for enemies of the other . It was also decided that Birger ' s daughter , Rikissa Birgersdotter , would marry the son of Haakon , Haakon the Young .