Birger was ousted by his brothers' supporters in 1318 and eventually went into exile under his brother-in-law King Eric VI of Denmark, taking the Royal Archives with him. His 18-year-old son Magnus had arrived that year with Danish troops to save Birger but an army under Canute Porse defeated them at Söderköping, practically putting an end to the conflict. Birger first fled to Gotland and left Magnus to defend the important Stegeborg Castle. Magnus was captured there only to be executed in Stockholm in 1320, with a younger brother Eric having died the year before and ex-king Birger dying in Denmark the year after. In 1319, the three-year-old son of Duke Erik, King Magnus VII of Norway, had then already been hailed King of Sweden after the short regency of his mother Duchess Ingeborg.