Duchy of Lauenburg ( ) is the southernmost Kreis, or district, officially called District of Duchy of Lauenburg (), of Schleswig-Holstein, Germany. It is bordered by (from the west and clockwise) the district of Stormarn, the city of Lübeck, the state of Mecklenburg-Vorpommern (districts of Nordwestmecklenburg and Ludwigslust-Parchim), the state of Lower Saxony (districts of Lüneburg and Harburg), and the city state of Hamburg. The district of Herzogtum Lauenburg is named after the former Duchy of Saxe-Lauenburg.
Geography
The district's territory comprises most of the former Duchy's territory north of the river Elbe, except of the Amt Neuhaus. All the former Saxe-Lauenburgian areas beyond the Elbe belong today to the Lower Saxon districts of Cuxhaven (Land of Hadeln), Harburg and Lüneburg.
The district's area contains a number of historically important towns, e.g. Lauenburg, Mölln and Ratzeburg. This importance was due to the Old Salt Route (Alte Salzstraße), one of the major medieval trade routes. Salt from the salt-works south of the Elbe river was transported northward to Lübeck. The transport of salt was also the motive for constructing the oldest artificial waterway of Europe, the Stecknitz Canal (1398). It was replaced in 1900 by the Elbe-Lübeck Canal.
The landscape is characterised by numerous lakes, forming the Lauenburg Lakes Nature Park. The largest lake is the Ratzeburger See with an area of 16 km<sup>2</sup>.
History
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. 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 in 1282, Albert II ruled with his still minor nephews Albert III, Eric I and John II, who by 1296 definitely partitioned the duchy 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 dukes dates back to 1295. A deed of 20 September 1296, circumscribing Saxe-Lauenburg, mentions the Vierlande (now Hamburg), Sadelbande (Land of Lauenburg), the Land of Ratzeburg, the Land of Darzing (later Amt Neuhaus), and the Land of Hadeln (the latter two now Lower Saxony) as the joint territory of the brothers, separate of Saxe-Wittenberg.