Hvem giftede sig med Johann I.?

John (c. 1242 – 13 December 1277), a member of the House of Welf, was Duke of Brunswick-Lüneburg from 1252 until his death. He initially reigned jointly with his brother, Albert the Tall, until the partition of the duchy in 1269, when John became the first ruler of the newly created Principality of Lüneburg.