Königsberg, as a fortress, was built and rebuilt throughout the centuries, and the culmination of these continuous reconstructions was a powerful ring system of city forts, erected in the 19th century, blocking the approaches to the city. The ring was located about 5 kilometers from the city walls and consisted of 12 large and 3 small forts. The diameter of the ring was about 13 kilometers, with a total length of more than 40 kilometers. The distance between the forts was 2–4 kilometers, which ensured visual and fire communication between them. Where this was impossible due to terrain conditions, small (lettered) forts were arranged in the gaps between the large forts. They were significantly smaller in size and housed a garrison of up to a company with several cannons. The usual garrison of a fort consisted of 200–300 soldiers and 30–40 guns. The buildings of both large and small forts (casemates, caponiers, barracks) were brick with vaults at least 1 meter thick. A layer of earth about 3 meters thick was planned above the structures. All forts were given proper names in honor of famous German commanders and kings.

Jermaine