Henry the Lion's grandson Otto the Child became duke of a part of Saxony in 1235, the new Duchy of Brunswick-Lüneburg, and died there in 1252. The duchy was divided several times during the High Middle Ages amongst various lines of the House of Welf. The subordinate states had the legal status of principalities within the duchy, which remained as an undivided imperial fief. Each state was generally named after the ruler's residence, e.g., the rulers of Brunswick-Wolfenbüttel originally lived in Wolfenbüttel.