King Birger's Treachery at Nyköping Banquet

King Birger of Sweden invited his brothers, Dukes Valdemar and Erik, to a banquet at Nyköping Castle under the guise of reconciliation. Instead, the king seized them and imprisoned them in a dungeon where they were left to starve. This betrayal was a significant act of political maneuvering within the Swedish nobility, showcasing the brutal nature of power struggles during the medieval period.