His reign was marked by unrest and civil strife; he was imprisoned by his brothers Erik and Valdemar following the "Håtuna games" in 1306, but when he tried to play them the same trick in Nyköping, there was an uprising that ended with Birger losing the crown and the execution of his 18-year-old son Magnus.

Duke Erik tried to establish an independent kingdom around Bohuslän, which he had received as part of his marriage to the Norwegian princess Ingeborg, and Halland at the boundary between Sweden, Norway and Denmark.

Birger remained king in name, but had to give up the Royal Domain, exchanging it for eastern Uppland, Närke, his brother Erik's former Duchy Södermanland, Östergötland, Gotland and the Castle of Viborg.

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.

[5] Birger had the following children with Martha:[6] In 2003, the band Falconer released The Sceptre of Deception, a concept album based on this period of Swedish history.