Rethmar Manor

The first lords of Haus Rethmar were the von Rutenbergs, who moved here from Rautenberg (formerly Rutenberg), located northeast of Hildesheim. Exactly when they came to Rethmar is uncertain. In any case, when the Counts of Haimar moved to Wernigerode in the 12th century (where they henceforth called themselves "von Wernigerode"), they took over extensive property from them. Where the main building of the castle is located today, around the year 1000 lay "the fortified house on the Worthberg", a castle surrounded by water and swamp from the then strongly flowing Dunaue, which the Rethmarers today call "Donau", making it practically impregnable. Brick and ceramic finds date the beginnings of the main house to the year 1009 and the west wing to the year 1064. Judging by the still quite high groundwater level today, the underground passage to the church, suspected by some chroniclers, could not have existed. However, there was probably a covered wooden bridge as access to the north, where St. Katharinenkirche was built only later. The castle gradually transformed through many alterations and additions. The west wing was erected around 1530. The Rutenbergs were at times in the service of the Bishop of Hildesheim, but were independent enough to pursue their own policies. The castle in Rethmar withstood a siege in 1332 by the bishop elected by his cathedral chapter and his allies. The von Rutenbergs had sided with the anti-bishop appointed by the Pope.

In 1647, Haus Rethmar passed to the son-in-law of the last local Rutenberg, a Lord of Eltz, whose son Philip Adam, Lord of Eltz, rose to minister at the court of Elector Georg I in Hanover. In 1694, he was among the murderers of Count Königsmarck. Königsmarck was a Hanoverian officer and the lover of Sophie Dorothee, the wife of Duke Georg Ludwig, later Elector and from 1714 King of Great Britain and Ireland. At that time, affairs in the highest families were not taken lightly. However, Königsmarck and Sophie Dorothee displayed theirs too publicly. Königsmarck was murdered in the Leineschloss in Hanover, and his body was probably sunk in the Leine, but not transported to Rethmar, as is sometimes claimed. Lord of Eltz then miraculously came into great wealth and was able to thoroughly rebuild and expand Haus Rethmar. The castle received its present form during this time. Sophie Dorothee, however, was divorced and interned for life as "Princess of Ahlden" on the Aller.