The castle was built around 1218 by
Gunzelin of Wolfenbüttel and his descendants of the
House of Asseburg, as a so-called
Ganerbenburg, or castle managed and occupied by more than one family or branch. Based on its dimensions, this elongated fortification was the largest
hill castle in
North Germany and was considered impregnable. Its purpose was to secure the lands around Wolfenbüttel. When Gunzelin refused to swear allegiance to Duke
Albert I of Brunswick-Lüneburg, of the
House of Welf, in 1255, the latter destroyed Gunzelin's
Wolfenbüttel Castle and sieged Gunzelin's son
Burchardus de Asseburc (
Burchard or
Busso of Asseburg) at Asseburg Castle. Burchard was able to withstand during three years, however in 1258 had to relinquish the castle to Duke Albert I. Burchard was then allowed to retreat to Westphalia with his knights, and received a compensation of 400 gold mark for the castle. After Gunzelin's death in 1260, his sons also lost the county of
Peine to the bishop of Hildesheim. Asseburg became one of the strongest fortresses in the duchy. In 1330 the dukes had to pledge the castle to the city of
Brunswick, which was interested in securing the trade routes below. When
Duke Henry IV asked the castle back in 1492, threatening another siege, the garrison set fire on the castle and left. It fell into ruins after it was abandoned. == Literature ==