Eric I, Duke of Schleswig

After the death of his elder brother Duke Valdemar III in 1257, Eric inherited the claim to the Duchy of Schleswig.

However, his uncle and potential feudal overlord King Christopher I of Denmark refused to install him as duke.

Subsequently, Eric participated in the coalition of Bishop Peder Bang of Roskilde and Prince Jaromar II of Rugia against King Christopher.

The Queen Dowager, Margaret Sambiria, acting as regent for her under age son, feared aggression from the Duke.

In 1268, he acquired Gottorp Castle from Bishop Bonde of Schleswig, who then moved his residence to Schwabstedt.

The seal of Eric I, the first known example of the coat of arms of Schleswig .