December 11 In Swedish History
1317: The 'Nykoeping Banquet,' not as cheerful as it sounds like takes place at a castle an hour's ride [today] south of Stockholm; in Swedish "Nyköpings gästabud" at Nyköpingshus. The banquet was King Birger of Sweden's Christmas celebration, and among the guests were his brothers Duke Valdemar and Duke Eric - both to be imprisoned later that night and starved to death in the dungeons of Nyköpingshus (the Nyköping Castle). Previously, the king's two brothers had staged a coup against him (referred to as "Håtunaleken," the Håtuna games).
The kings of Denmark and Norway intervened, and a settlement was reached in 1310 (Sweden was divided among the brothers into three sovereign states). So when Valdemar and Eric were invited, it was looked upon as a sign of reconciliation.

However, after they both had retired to their chambers, King Birger's Seneschal Johan von Brunkow arrived with a company of crossbowmen and manacled them. The following morning, the dukes' retinue was also apprehended.

The dukes knew that no mercy would be forthcoming from Birger so they had their testaments drawn up after five weeks in the dungeon. These testaments, dated January 18, 1318, are preserved into modern times. Soon thereafter both dukes died in the dungeon, according to tradition by drawn-out starvation.