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In page District of Duchy of Lauenburg:

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The district Herzogtum Lauenburg is named after the medieval Duchy of Saxe-Lauenburg, which was one of the remnants of the original Duchy of Saxony. The Duchy of Saxony was partitioned in a process started in 1269, nine years after in 1260 Albert II and John I had succeeded their father Albert I of Saxony.[1] In 1269, 1272 and 1282, the brothers gradually divided their governing competences within the three territorially unconnected Saxon areas along the Elbe river (one called Land of Hadeln, another around Lauenburg upon Elbe and the third around Wittenberg upon Elbe), thus preparing a partition.[citation needed]