Meanwhile, after Albert I's death in 1260, the Duchy of Saxony was co-ruled by his sons John I and Albert II, and subsequently also by John I's sons. However, the geographic separation of the territories – Wittenberg, Lauenburg and Hadeln – led to them being increasingly administered separately. In 1296 the duchy was officially separated into two separate duchies: John's sons became rulers of Saxe-Lauenburg (which also included the Hadeln exclave) while Albert II became ruler of Saxe-Wittenberg. In addition to the duchy, Albert had acquired the County of Gommern in 1295, and in 1290 his son and heir Rudolph had been enfeoffed with the lands of the former County of Brehna on Wittenberg's southern border. The status of the electoral dignity was contested by both lines until it was officially settled in Saxe-Wittenberg's favour by the Golden Bull of 1356, after which time it became known as the Electorate of Saxony. In 1423 the Electorate was inherited by the Wettin Frederick I, who was also the Margrave of Meissen and Landgrave of Thuringia. Since Prince-elector was a higher rank than either landgrave or margrave, the whole of Frederick's territory became known as the Electorate of Saxony; the lands around Wittenberg, Brehna and Gommern became known as the "" or "Electoral Circle".