Wintershall Holding GmbH, based in Kassel, was Germany's largest crude oil and natural gas producer.

The company was active in oil and gas exploration and production with operations in Europe, North Africa, South America as well as Russia and the Middle East region.

[3] The name Wintershall (pronounced: Winters·hall) is derived from the surname of Carl Julius Winter and the Old High German word for salt (Hall, see halite, halurgy).

[4] Ground was first broken on 23 April 1900 to drill the Grimberg shaft at Widdershausen, and the first Wintershall potash works were built in Heringen.

[7] Rosterg maintained close ties with the NSDAP elite and met the commander of the SS, Heinrich Himmler, personally on several occasions.

The American military government considered Rosterg, as a member of “Himmler’s circle”, to be a “captain of industry under the National Socialist regime”.

As a result, NITAG became the main sales subsidiary for mineral oil products alongside Mihag, Wiesöl and Wintershall Mineralöl GmbH.

[9][10] In the post-war era, Wintershall lost a large oil refinery in Lützkendorf, some of its NITAG service stations and the potash shafts and works in Thuringia due to expropriation in the Soviet Occupation Zone.

[8][18] In 1987, Wintershall began operating the Mittelplate drilling platform on the edge of the Schleswig-Holstein Wadden Sea National Park along with DEA in a 50:50 joint venture.

[19] More than 35 million tonnes of crude oil have been produced to date by the relatively small production island, which measures just 70 by 95 metres (230 by 312 ft).

[23] European unbundling regulations meant that network operation and storage had to be split from natural gas trading and transferred to separate companies.

As a result of an asset swap between BASF and Gazprom, the new Wingas and hence Wintershall's natural gas trading activities were fully transferred to Russian ownership in 2015.