In the night from 6 to 7 May 1223, he abducted Valdemar II and his son Valdemar the Younger from the Danish island of Lyø, near Funen, where Valdemar was resting without his bodyguard, after he had been hunting.
Pada malam hari dari tanggal 6 sampai 7 Mei 1223, dia menculik Valdemar II dan putranya Valdemar Muda dari pulau Denmark Lyø, dekat Fyn, tempat Valdemar beristirahat tanpa pengawalnya, setelah ia berburu.