Eric I of Schleswig

Eric I Abelsøn (c. 1241–1272), second son of Abel, claimed Schleswig after his brother Valdemar III's death in 1257, but his uncle Christopher I withheld the duchy. In 1259 he joined the bishop and Jaromar II of Rügen in taking Copenhagen. Made duke in 1260, he defeated Regent Margaret Sambiria at Lohede in 1261, capturing Eric V.

The 1264 peace granted him all crown lands in Schleswig and Als. He died in 1272, leaving Gottorp and the duchy to his son Valdemar IV.