Fort No. 7 "Herzog von Holstein" — one of the forts that were part of the defensive system known as the "Night Quilt of Königsberg," a monument of 19th-century fortification art. Located just west of the Pregolsky microdistrict, the fort is possibly the strangest and most mysterious among all its Kaliningrad counterparts. In fact, it is not even clearly understood who it was named after. Local historian Avenir Ovsyanov, in his book “In the Casemates of the Royal Fort”, points out that there were many Dukes of Holstein (Holstein) in East Prussia. “Duke Friedrich Ludwig von Holstein-Beck (1653–1728) is known as a military figure who advocated for the preservation of statehood and ensuring Prussia’s neutrality during the Great Northern War (1700–1721). Duke Friedrich Wilhelm von Holstein-Beck (1687–1749) served under King Frederick II. In 1741, he became a field marshal. There was also Duke Peter August von Holstein (1698–1775). The rank of General Field Marshal was conferred upon him in 1762 by Russian Emperor Peter III, when he served in the Russian army,” the historian reports, concluding that, most likely, the fort bears a collective name in honor of the Holstein dynasty, descending from the Oldenburg counts of Northern Germany. Members of the Holstein family were prominent military and state figures of Prussia, and their blood flowed through the veins of many European royal families.

The area between the two-tier bridge and the railcar factory in Königsberg was called Holstein Damm — today this is the Right Embankment, and on the site of the present-day Pregolsky settlement was the Gross-Holstein estate. Nearby, from 1887 to 1890, a fort was built to cover the Königsberg sea canal and the entrance to the mouth of the Pregel (now the Pregolya River). In the book by Russian fortification expert Yakovlev, “History of Fortresses,” dedicated to defensive architecture from ancient times to the early 20th century, three forts were listed under number 7 in Königsberg — No. 7, No. 7a, and No. 7b. The first two were located on the left bank of the Pregolya, the third on the right, and by the beginning of World War II, only the latter existed. Most likely, the forts on the left bank were only planned but never built due to the rapid development of artillery, which rendered them useless. Therefore, the "Herzog von Holstein" fort is probably not the main No. 7 but the intermediate No. 7b, which is confirmed by the typical pentagonal shape and similar construction characteristic of lettered forts. The bastion casemates are connected by a sally port to the casemates of the central part, which have a two-tier structure. There is a brick counterscarp with five coffers and a passage connecting them inside the counterscarp wall. The fort is surrounded by a water-filled moat.

As for the fort’s structures, it is unique and unlike any of its 11 large counterparts. The "Herzog von Holstein" was built in the form of a closed pentagon — in the style of a bastion. The peculiarity of the "Herzog" is the absence of caponiers and demi-caponiers. Instead, defensive structures with embrasures were built in the corners of the moat’s faces (sides). Everything was designed so that the water-filled moat could be covered by rifle and machine-gun fire on every section. Communication between the coffers is carried out through a sally port (corridor, gallery) within the counterscarp itself.

During the assault on Königsberg by the Red Army in April 1945, the fort was away from the main directions of attack. In the memoirs of General Beloborodov, it is noted that on April 10, fire from self-propelled artillery units at close range suppressed the firing points, after which units of the 84th Guards Rifle Regiment captured the fort almost without losses, taking more than 250 prisoners.

Since 1947, the fort belonged to the Ministry of Defense enterprise "Artillery Repair Plant No. 69," and since August 2021 — to PTB "Granit," part of the Almaz-Antey concern. Access to its territory is closed.

Sources:

https://day-off39.ru/otdykh-v-kaliningrade-i-oblasti/kaliningrad/8782-fort-7-gertsog-fon-golshtejn

https://strana39.ru/news/nash-kray/99813/gertsog-fon-golshteyn-zagadochnyy-i-neobychnyy-.html