Sealed former potash shaft site of Schacht Sachsen (Bernterode II) in Bernterode-Schacht, where above-ground structures were largely destroyed in the July 1945 munitions explosion.
Schacht Sachsen, also known as Bernterode II, was the second production shaft of the Kaliwerk Bernterode operated by the Aktiengesellschaft Deutsche Kaliwerke in the village of Bernterode-Schacht in the Eichsfeld. Production began in 1912, one year after a rail connection was upgraded to a full station, and the shaft operated alongside Schacht Preußen (Bernterode I) until both were closed in 1931 during the Weltwirtschaftskrise. The abandoned mine buildings and underground workings were converted from 1936 into the Heeresmunitionsanstalt Bernterode, which began producing and storing munitions from 1938.
The first munitions storage trials in any German kali mine had taken place here in May 1934, confirming that hard salt workings were suitable for the purpose while carnallite cavities were not. In March 1945 Prussian royal coffins, military standards, and cultural property from Berlin were hidden in the underground workings; these were recovered by US forces before they withdrew on 2 July 1945. On 4 July 1945 a munitions train on the works railway exploded, destroying most of the above-ground plant and structures at both shafts.
Schacht Sachsen (Bernterode II) is situated 1 kilometre northwest of the older Bernterode-Ort in the settlement of Bernterode-Schacht, which was built to house the mine workforce when the kali works opened. Its coordinates lie only a few tens of metres from those of Schacht Preußen (Bernterode I), confirming the two shafts occupied a closely grouped site.
Preparations for the Kaliwerk Bernterode began in 1904 with the founding of the Aktiengesellschaft Deutsche Kaliwerke for the Bernterode site. Production in Schacht Preußen commenced in 1905–06. A Chlorkaliumfabrik was commissioned in 1907. In 1911 the Haltestelle on the Bahnstrecke Halle–Hann. Münden was upgraded to a full Bahnhof with a dedicated rail connection to the shaft complex. Production in Schacht Sachsen (Bernterode II) commenced in 1912. With the move of the company administration to Bernterode the site became the corporate headquarters of Deutsche Kaliwerke.
The company also acquired the Kaliwerk Ludwigshall in 1913 and the Kaliwerk Immenrode, extending the Deutsche Kaliwerke concern significantly. Both Bernterode shafts were closed in 1931 during the Weltwirtschaftskrise when the economic conditions for continued potash production collapsed.
In May 1934 the first munitions storage trials in any German kali mine took place in the Bernterode workings, then designated the Kalibergwerk Preußen-Sachsen. The trials established that carnallite workings were unsuitable because their hygroscopic properties caused condensation and consequent corrosive attack on munitions; hard salt workings were found to be suitable. From 1936 construction work began on the conversion of the mine buildings and underground workings into the Heeresmunitionsanstalt Bernterode. Munitions production and storage began in 1938. In the Südharz region, Bernterode was one of five Heeresmunitionsanstalten alongside Kleinbodungen, Obergebra, Sondershausen, and Wolkramshausen.
In March 1945, as the Allied forces approached Berlin, significant cultural and historical material was hidden in the Bernterode workings: the coffins of Paul von Hindenburg and his wife, and of the Prussian kings Friedrich Wilhelm I and Friedrich II; the flags and standards of the German army from 1914–1918; archival records of the Auswärtiges Amt and the Katasteramt Kassel; paintings from Prussian state museums; the library of Sanssouci; the Prussian crown jewels; valuable porcelain; and 271 paintings in total. US forces that occupied Bernterode in the war's final phase transferred most of this material to the Marburg Central Collecting Point before withdrawing from the area on 2 July 1945. Two days later, on 4 July 1945, a munitions train on the works railway exploded, destroying the Bahnhof and most of the above-ground plant and structures of the mine.
In 1953 the mine came under the administration of the Kaliwerk Sollstedt, and parts of the underground workings were retained in connection with the broader Südharz potash operation.
In the 2020s South Harz Potash Limited and its German subsidiary Südharz Kali GmbH proposed using the Bernterode shaft complex — encompassing both the Bernterode I and Bernterode II shaft sites — as key surface infrastructure for a new potash mining project targeting the Ohmgebirge deposit. The project plans included use of the shaft access infrastructure and the nearby Bernterode Bahnhof site.