The two siblings were adopted by their grandaunt Queen Margaret I of Denmark in 1388 and likely brought to Margaret at the same occasion. Initially, Margaret's plan was for Catherine to enter the Vadstena Abbey[1]
Catherine was a candidate for a time for marriage to Henry, Prince of Wales.[2] This marriage was suggested in 1400–1401, and it was the idea that a double wedding was to be arranged between Catherine and Henry in parallel to the wedding between her brother Eric and Henry's sister Philippa.[3]
The marriage between Catherine and Henry never occurred and was broken off in 1404. The English had wished for Catherine's children with Henry to inherit the Nordic thrones in the case of Eric dying without an heir (which was impossible since the Kalmar Union was elective), as well as an alliance against France, which Margaret could not agree to.[4] In 1406, another indirect link to the English royal house was created when the brother-in-law of Philippa (Louis III, Elector Palatine) suggested a marriage with John, Count Palatine of Neumarkt.[5] John was the son of Rupert, King of Germany. An alliance with the German king was more valuable for the Nordic Union considering their problem with the Hanseatic League.[6] The negotiations were completed in one year, and Margaret gave Catherine a dowry of 4,000 gulden, much less than was expected by her future father-in-law.
On 15 August 1407, Catherine married John in Ribe, Denmark. They would have seven children, but only their youngest, Christopher, lived past infancy. Christopher succeeded his uncle Eric as king of the three Scandinavian kingdoms.
