Fort No. 4 "Gneisenau" is named after August Wilhelm Antonius Graf Neidhardt von Gneisenau (Count August Neidhardt von Gneisenau, a German military commander). Gneisenau demonstrated his military skill in 1807 by organizing the defense of the fortress Kolberg. French troops failed to capture it. He was an ally of Russia in the fight against Napoleon. The construction date of the structure has not been established. There is no information in cultural heritage directories or post-war publications. The approximate construction dates are between 1872-1886. The only German source (a book by Hermann Frobenius published in 1906) reports the dates 1876-1881.

The fort has a classic elongated hexagonal shape typical for that time, surrounded by a moat filled with water. The two-story fort buildings are made of brick and covered by an earthen rampart up to 3 meters thick. The garrison numbered 260-300 men, armed with small arms and about 40 artillery pieces, and was capable of withstanding a prolonged siege. By the beginning of the 20th century, it had become obsolete but was repeatedly modernized thereafter.

During the fighting in April 1945, it sustained significant damage. In the post-war period, it was under the jurisdiction of the Ministry of Defense.

In the post-war years, the central gorge part of the fort was completely destroyed, with roads laid to its right and left. It represents an elongated hexagon along the front, surrounded by a water-filled moat. The two-story central building with internal rooms and two inner courtyards with combat positions are symmetrically located on both sides of the central sally port, covered by an earthen embankment.

The difficulty in establishing the construction date lies in the absence of a foundation stone in the gorge part of the fort at the entrance to the central sally port. The gorge part is completely destroyed. It is located in the northern part of Kaliningrad. After the war, the fort served as a training ground for sapper and mine-explosive unit experiments.

Fort No. 4 was located north of Königsberg in the advance sector of the 124th Rifle Corps. On maps and combat reports, it was mistakenly called "Friedrich Wilhelm." Before the assault, it was subjected to destruction by heavy artillery of special power, the 226th artillery division, with 280 mm caliber guns. The report states the following:

Firing was conducted on a high trajectory at an elevation angle of more than 45 degrees using concrete-piercing shells with KTD fuses set for long delay. Conditions for firing were very unfavorable; it rained throughout the three days of preliminary destruction, and due to poor visibility, the fort was completely obscured. The firing officers could not observe the air bursts as they were hidden behind trees growing on the fort's surface, and moreover, the large area of the fort did not allow distinguishing direct hits.

From April 2 to 6, the division expended 560 shells of 280 mm caliber.

As a result of the firing, 23 through-holes were noted in the brick-concrete masonry of the fort, causing the following damage:

- The underground communication passage to the central casemate was blocked.

- The combat ceiling of the sally port—the deepest communication passage, protected on top by 1.5 m of brickwork and 7 m of earth embankment—was breached.

- Two hits completely destroyed the superstructure of the western half-caponier, damaging the northern wall, the upper combat ceiling, and two underground meter-thick brick-cement ceilings.

- Six hits in the western barracks destroyed the common corridor and three casemates in two places.

- The entrance to the fort’s inner courtyard from the central building was destroyed and blocked.

- Two casemates in the eastern barracks were destroyed by a direct hit.

- The underground communication passage leading from the inner western courtyard to the western half-caponier and barracks was blocked.

- Underground passages to the eastern half-caponier were destroyed and blocked.

- Two hits partially destroyed the eastern half-caponier, making its combat use impossible.

- Three hits destroyed the counterscarp (outer wall of the moat), facilitating the assaulting units to overcome the 25 m water moat.

- The exits from the inner eastern courtyard to the corridor and barracks were completely destroyed and blocked.

- Two hits completely destroyed and blocked a three-story building adjacent to the eastern half-caponier.

The above structural damages during combat operations are irreparable. Other rooms in the fort have numerous cracks. Such damage morally crushed the remaining garrison personnel, greatly facilitating the infantry assault on the fort, as confirmed by prisoner testimonies. The fort commander committed suicide.

Assault group reports provide the following information:

"Enemy units of the 75th Guard Regiment stubbornly defend the approaches to the city of Königsberg on the line of Neuhofen and Fort No. 4. They hinder the successful advance of our troops. Dimensions are 160 by 200 meters, earthen rampart height up to 4 meters, moat up to 35 meters wide filled with water, in front of the fortifications are trenches, wire obstacles, and the approaches are covered by fire from caponiers."

On April 6, 1945, at 22:00, it was captured after an intense attack. Up to 50 enemy soldiers and officers were killed, 5 were taken prisoner. The fort commander shot himself.

Trophies:

- Machine guns: 5,

- Rifles: 25,

- Submachine guns: 20.

Sources:

https://gid39.su/fort-4/ — blog by Nikita Zagorny

https://day-off39.ru/otdykh-v-kaliningrade-i-oblasti/kaliningrad/5942-fort-4-gnejzenau