In the midst of the Northern War with Sweden, in the autumn of 1703, the new city of Saint Petersburg needed reliable protection from the sea. Peter I was fully aware of this. As soon as it became known from a letter by A. Menshikov to the tsar that a squadron of nine Swedish ships under the command of Vice Admiral Numers, stationed near the island of Retussari and blocking the sea exit from the Neva Bay, had gone to winter quarters in Vyborg, the Russian yacht and galiot under the Sovereign’s command rushed into the Gulf of Finland. During the movement of the vessels, Peter personally measured the depths. The northern part of the gulf, due to numerous rocks and shallows, proved unsuitable for navigation. Only near the southern coast of the island was a narrow fairway found, through which enemy warships could reach the under-construction Saint Petersburg. There, a vast shoal stretching to the southern shore of the gulf was also discovered. Peter I immediately recognized the strategic importance of the island, as if nature itself had created it for building the future maritime outpost city on the Neva. He did not waste time. He decided to build a piled fort on the shoal, and opposite it—at the narrowest part of the fairway—to construct a coastal battery to block the enemy ships’ path with crossfire artillery. This was accomplished in the shortest time.

Upon arriving in Voronezh in October, Peter personally made a wooden model of the fort and sent it to Menshikov in Petersburg, entrusting him with secretly constructing the first fortifications of the fortress he envisioned on Kotlin Island during the winter and spring of 1704, hidden from the Swedes. The construction was carried out by soldiers of the Tolbukhin and Ostrovsky regiments under the overall supervision of bombardier Vasily Korchmin. Pre-prepared logs, stones, and soil were transported on sledges over the ice to the future fort’s site. Then soldiers and workers assembled “ryazhi”—log boxes 10 meters long and 2–3 meters high—and filled them with cobblestones and earth. After that, they cut the ice around the ryazhi, and they sank to the bottom of the shoal. Another row of log boxes was placed on top. Gradually, using ancient Russian technology (used for building dams and bridge supports on rivers), an underwater artificial foundation for the fort was created. Additionally, sheet pile piles were driven around the ryazhi and backfilled with stones to prevent them from being destroyed or shifted by wave impacts. When a log platform was laid on the foundation nearly one meter above the water, construction began on the walls of the ten-sided, three-tiered wooden and clay tower of the fort, featuring loophole windows and a tented roof topped with a signal lighthouse and flagpole. The fort’s height was 36.5 meters, width 29 meters. Thus, the world’s first sea fort with an artificial foundation was built. Previously, forts of sea fortresses in other countries were built either on the shore or on rocks.

On May 7 (18), 1704, Peter I set out from Saint Petersburg to Kotlin Island on several vessels. By his orders, fourteen 6-pounder guns were installed in the fort’s embrasures. Then the Novgorod Metropolitan Iova performed the consecration ceremony of the new Russian fortress, named “Kronshlot” (Crown Castle). This day is now celebrated as the founding day of Kronstadt.

The tsar was proud of the fort’s construction and valued it, understanding its strategic importance. Notably, even before the official opening and consecration of Kronshlot, he personally drafted instructions for the fort’s garrison:

“1. Preserve this site with God’s help, even if it comes down to the last man, and when the enemy tries to break past it, then shoot only when they come closer and do not rush the firing, but shoot so that after the last cannon shot, the first is ready again, and do not waste cannonballs needlessly.

2. When neutral ships appear under their own flags of any state and begin to approach the fortress, then at such a distance as can be reached by a cannonball, fire without cannonballs so that they lower their sails and drop anchor; and if they do not obey, then shortly fire cannonballs past the ship; and if they still do not obey, then, having waited, fire as at the enemy. It is necessary to understand that from the first shot to the second there should be a little more than a quarter of time so that they can drop anchor in time.

3. If a ship drops anchor and a skipper comes to the citadel in a boat, he and all those with him must be honestly detained by the guard, and meanwhile someone should be sent from the citadel in boats to inspect the ship everywhere, including under the lower deck, to see if there are any people secretly hidden, as well as weapons and other supplies, and if none are found, release them and order them to leave, providing pilots. Meanwhile, until someone comes from the ship in a boat to the citadel, no one should be sent from the citadel to the ship.

4. When a ship passes by the citadel, it is necessary to lower the foremast or mainmast as a salute, and if there is a pennant, to take it down until the citadel is passed; and from the citadel, fire with the fort’s guns less, and about the removal of the pennant and lowering of sails, inform them when they arrive at the citadel.

5. It is very necessary to beware of enemy fire ships. The difference from other ships is that they have two hooks on the bowsprit, as shown here. Also, one should beware of their fire due to the abundance of wood.”

Peter the Great (unknowingly) with the construction of Kronshlot and later the coastal fortifications of the central fortress anticipated foreign fortification engineers by almost a century, founding the world’s first fort fortress Kronstadt (with sea and coastal forts placed beyond the defensive perimeter of the main fortress).

Simultaneously with the fort’s construction, whose garrison numbered about 70 men, the first coastal battery consisting of eight guns was erected on the southern shore of Kotlin Island. It stood opposite Kronshlot and was later called the Old Battery. Just two months later, in July 1704, a Swedish squadron under Vice Admiral De Prou (about 40 sails) approached Kotlin Island. To the Swedes’ surprise, they found coastal batteries, a fort on the fairway, and Russian ships and scampavays (half-galleys) of the young Baltic Fleet nearby.

On July 12, at the western tip of the island, the Swedish landing began using boats. As they approached the shore, they were suddenly fired upon by musket volleys from soldiers of the Tolbukhin regiment, who were hidden among trees, bushes, and rocks. The enemies panicked and retreated with significant losses. Admiral De Prou then decided to attack the Russian fort. For two days, the Swedes bombarded Kronshlot with their ship guns but failed to hit it due to the distance. Meanwhile, the accurate return fire of our artillerymen inflicted considerable damage on the enemy ships. As a result, the Swedish squadron raised sails and was forced to retreat back to Vyborg.

Thus, through the timely construction of the first fortifications on Kotlin Island and the valor of Russian soldiers and sailors, the glorious combat chronicle of Kronstadt began. It later became the strongest and most impregnable sea fortress not only in Russia but in the world, never captured by foreign invaders. Moreover, during the 18th–19th centuries, Kronshlot was the only sea fort of the Kronstadt fortress that actively participated in battles repelling attacks by enemy fleet ships attempting to break through to Saint Petersburg.

The fort “Kronshlot” wrote another important page in the history of the fortress city and the Russian Navy when, by order of Peter the Great on November 16 (27), 1705, the (regular) Naval Regiment was formed there. This day became the birthday of Russian naval infantry. Colonel Treiden was appointed its commander—the first commandant of the fort. The officer corps of the Naval Regiment was staffed by non-commissioned officers from the Life Guards Preobrazhensky and Semyonovsky regiments, who trained and educated their soldiers and, together with them, gained combat experience during the Northern War: in boarding fights of naval battles and landings on enemy coasts. During navigation, the galley (rowing) fleet was anchored near Kronshlot’s fairway, used for transporting naval infantry and conducting combat operations involving them. Along with the fort’s artillery and coastal batteries on Kotlin, the rowing warships were another obstacle to prevent possible enemy ship breakthroughs to Saint Petersburg.

After the Russian victory at the Battle of Poltava, a turning point in the Northern War with Sweden, Peter I again focused on the Baltic, particularly on building the fortress city and port on Kotlin Island. By then, it was clear that Kronshlot no longer met its defensive functions due to the small number of guns in the fort’s tower and required reconstruction. In 1717, major expansion works began on the fort, completed by 1724. Now Kronshlot, in addition to the old tower, had fortifications in the form of an elongated pentagon bastion layout, built on a piled foundation, where 120 guns were installed. Additionally, a small inner harbor appeared at the fort, where rowing fleet ships could dock.

However, by the mid-18th century, the Kronshlot tower had completely deteriorated and was dismantled. Two options for building a new tower were developed but ultimately abandoned, as it no longer met the fortification requirements of the time. Meanwhile, between 1783 and 1789, Kronshlot—its bastions, curtains, and harbor walls—were the first in the Kronstadt fortress to be rebuilt in stone. On the site of the famous tower’s foundation from the Peter’s era, a polygonal base clad with granite slabs was erected, which has survived to this day. It was planned to build a stone naval prison on it, but fortunately, this idea was abandoned.

The next modernization and reconstruction of the “Kronshlot” fort occurred during the so-called “stone construction” period of the Kronstadt fortress. In many European countries and Russia, this was the era of building multi-tiered casemated forts and batteries armed with bombarding guns, considered more advanced, longer-ranged, and reliable than old smoothbore cannons.

In 1808, an octagonal brick powder magazine building with a tented roof was erected in the eastern corner of Kronshlot’s harbor. It still strongly resembles the old wooden-earth tower of the fort in appearance. Many tour guides are unaware of this and still mistakenly call it the old Kronshlot.

From 1850 to 1863, the Nikolaev Casemated Battery was built on the western defense face of Kronshlot fort, designed by fortification engineer Zarzhetsky. Its armament included several powerful bombarding guns of the Maievsky system, then the best in the world, capable of firing dagger-like direct fire along the entire Great Kronstadt Roadstead at a distance of nearly 4.5 km. The guns were placed in embrasures of the lower casemated tier of the battery, built of brick and protected externally by granite blocks nearly 3 meters thick. The upper (open) tier of the battery was made of wood and earth, where guns of the fort also stood behind the parapet.

However, artillery and fortifications continued to improve, and by the late 19th century, casemated fortifications of land and coastal fortresses became completely obsolete. Rifled artillery, more long-ranged and rapid-firing, replaced smoothbore guns. As a result, in 1896, Kronshlot fort was removed from the fortress’s combat composition and disarmed. Its buildings and structures gradually fell into disrepair.

In 1906, during preparations for the celebrations dedicated to the 200th anniversary of the Kronstadt fortress’s founding, Kronshlot was remembered. The fort’s territory, building, and inner yard of the Nikolaev battery, as well as the harbor pier, were tidied and decorated with flags. On May 9, 1906, when honored guests with ladies landed on the fort from cutters, they were greeted not only by the garrison soldiers standing in parade formation but also by sailors dressed as bombardiers and fusiliers of Peter’s time in tricorn hats. They stood near a unique old gun (from 1724 with a rectangular barrel bore, designed to fire a special projectile called a knippel). It consisted of two hemispheres connected by a chain to tear sails and rigging of enemy ships during naval battles.

Here is how the Kronstadt press wrote about this event: “At 11 o’clock, the fortress commandant Belyaev arrived with his wife. After receiving a report from the commander of the troops Adlerberg, he inspected the troops, greeting them. After a prayer performed by Mitrophoric Archpriest Father Ioann Sergiev and toasts to the Tsar, a 101-gun salute was fired. After proclaiming eternal memory to Emperor Peter the Great, a parade of all branches of the troops took place.”

Additionally, specially for the anniversary, which was planned to be held in 1904, a commemorative badge for the 200th anniversary of the Kronshlot fortress was ordered and made. In 1914, on the fort’s territory near the eastern (rear) facade of the Nikolaev battery building (on the wall of which memorial plaques honoring the builders of the fortification are still fixed), a granite stele was installed with the inscription: “To Peter the Great—the sovereign founder of Kronshlot.”

From the late 19th century until the 1930s, various naval engineering services, a mine station, and warehouses for fleet needs were located there. In 1879, instead of the upper open tier of the Nikolaev battery building, a second floor was built, housing the fort’s garrison barracks. Also, in 1897, on the fort’s territory, a sector light was constructed by specialists of the French company “Batinol” on order from Russia. Made of steel and painted red, it still stands on Kronshlot’s southern wall. Another lighthouse is located near the western wall of the Nikolaev battery but has long been out of use.

In the late 1930s, a massive reinforced concrete hangar building with a slipway was erected near the former powder magazine on the fort. In winter, combat boats of the Baltic Fleet stood and were repaired there on special foundations—keel blocks. The building still exists but is abandoned.

During the Great Patriotic War and the enemy blockade, two divisions of small marine hunters (MO) of the Kronstadt Water District Protection (OVR) were based at Kronshlot. The headquarters of the unit, from where general control of the patrol service in the eastern part of the Gulf of Finland was exercised, was also located there. The headquarters was housed in a one-story building at the fort’s eastern (round) tip, where the old wooden tower of Kronshlot stood in Peter’s era. On the second floor of the polygonal former powder magazine building were officers’ dormitories and a telephone station.

In the Nikolaev battery building during the blockade and postwar period, the first floor housed the personnel dining room, galley, and food warehouse. The second floor contained living quarters for petty officers and sailors, as well as a club with a cinema booth and a small stage. MO boats were moored at wooden piers in the southern part of the fort’s harbor. Nearby on the shore were the battery station, fuel, and ammunition warehouses. The fort had no anti-aircraft air defense battery. To repel enemy air attacks, the guns and machine guns of the “marine hunters” were used.

In 1945, the first ship degaussing station in the USSR was installed and opened on Kronshlot’s territory. Trophy German equipment was used for its outfitting. It was captured in the port city of Porkkala-Udd in Finland, where during the war one of the Kriegsmarine’s SRKs was located, invented by Nazi Germany’s engineers. They actively used it to degauss their warships and transport vessels. German stations were installed on railway platforms, and degaussing cables were underwater.

At Kronshlot, the station was installed in the northern wing of the former Nikolaev battery building. Its equipment and subsequent many years of uninterrupted operation ensured high secrecy and speed of the fleet’s ship degaussing process. The station at Kronshlot is still operational today.

Sources:

https://xn--80aiqmelqc4c.xn--p1ai/forty/fort-kronshlot/

https://ru.wikipedia.org/wiki/Форты_Санкт-Петербурга#Форт_«Кроншлот»

https://kronvestnik.ru/news/13935