The Duchy of Saxe-Lauenburg (, called Niedersachsen (Lower Saxony) between the 14th and 17th centuries; ), was a reichsfrei duchy that existed from 1296–1803 and again from 1814–1876 in the extreme southeast region of what is now Schleswig-Holstein. Its territorial center was in the modern district of Herzogtum Lauenburg and originally its eponymous capital was Lauenburg upon Elbe, though in 1619 the capital moved to Ratzeburg. Former territories not part of today's district of Lauenburg In addition to the core territories in the modern district of Lauenburg, at times other territories, mostly south of the river Elbe, belonged to the duchy: The tract of land along the southern Elbe bank (), reaching from Marschacht to the Amt Neuhaus, territorially connecting the core of the duchy with these more southeastern Lauenburgian areas. This land was ceded to the Kingdom of Hanover in 1814. It is now part of the Lower Saxon Harburg (district). The Amt Neuhaus proper, then including areas on both sides of the Elbe, which was ceded to the Kingdom of Hanover in 1814. Today, this is all part of Lower Saxon Lüneburg (district). The exclave Land of Hadeln in the area of the Elbe estuary was disentangled from Saxe-Lauenburg in 1689 and administered as a separate territory under imperial custody, before it was ceded to Bremen-Verden in 1731. Now it is part of today's Lower Saxon Cuxhaven (district). Some North Elbian municipalities of the former core duchy are not part of today's district of Lauenburg, since they had been ceded to the then Soviet occupation zone by the Barber Lyashchenko Agreement in November 1945. History Early history In 1203, King Valdemar II of Denmark conquered the area later comprising Saxe-Lauenburg, but it reverted to Albert I, Duke of Saxony in 1227. In 1260, Albert I's sons Albert II and John I succeeded their father. 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. After John I's resignation, Albert II ruled with his minor nephews Albert III, Eric I and John II, who by 1296 definitely partitioned Saxony providing Saxe-Lauenburg for the brothers, and Saxe-Wittenberg for their uncle Albert II. The last document, mentioning the brothers and their uncle Albert II as Saxon fellow