The 'Koivisto Landing Operation' was a Soviet small-scale amphibious undertaking by elements of the Baltic Fleet to seize the Finnish islands of the Koivisto archipelago to the south of Primorsk near the head of the Gulf of Finland during the 'Vyborg-Petrozavodsk Offensive Operation' (20/25 June 1944).

Otherwise known as the 'Bjork Landing Operation', this was the second of the three sub-operations together constituting the 'Vyborg-Petrozavodsk Offensive Operation', whose other elements were the 'Vyborg Offensive Operation' (10/20 June) and the 'Svir-Petrozavodsk Offensive Operation' (21 June/9 August).

During the southern part of the 'Vyborg-Petrozavodsk Offensive Operation', forces of General (from 18 June Marshal Sovetskogo Soyuza Leonid A. Govorov’s Leningrad Front had by 16 June cleared the Finnish troops of Kenraaliluutnantti Karl Lennart Oesch’s Karjalan Kannaksen Armeija (Army of the Karelian Isthmus) from the area of Koivisto (now Primorsk) on the northern side of the Gulf of Finland about midway between Leningrad and the Finnish city of Viipuri (Vyborg in Russian), and in heavy fighting advanced on Viipuri, which was taken on 20 June. At the same time, the islands of the Koivisto (now Beryozovye) archipelago, held by the Finns and thus off the left flank of the Soviet advance, which was thus exposed to possible Finnish reconnaissance and landings of the type that could threaten the Soviet lines of communication. Finnish retention of the islands also made difficult the movements of Admiral Vladimir F. Tributs’s Baltic Fleet from Leningrad to Viipuri Bay, where its ships could support the Soviet land forces. In order to remove this threat, on 19 June Govorov ordered the Baltic Fleet to occupy the islands of the Koivisto archipelago. It was noted that in view of the stubborn resistance of the Finns on the mainland front, the operation must be carried out by the fleet’s own forces. In anticipation of this tasking, as early as 17 June the Baltic Fleet had started to concentrate at the point of departure the means to carry and land the necessary troops, and also started to deliver reconnaissance groups on the islands. Minesweeping of the approaches to the islands was carried out, some 202 mines being found and destroyed, and the Baltic Fleet’s air arm was reoriented toward action over the archipelago.

Control of the operation was entrusted to Vitse Admiral Yuri F. Rall, the commander of the Kronstadt naval defence area, to whom the 260^th Separate Marine Brigade (some 1,500 men) was allocated, together with a force of small craft (four gunboats, eight armoured boats 16 patrol boats, 28 smaller craft, 18 smoke launchers and a number of minesweepers) to deliver, land and support the landed troops.

The Finns were well aware of the threat to the islands' garrison force of some 3,000 men with 40 pieces of artillery, and had already laid defensive minefields which were now hastily enlarged to protect the approaches to Transund and the islands of Björkö (now Bol’shoi Beryozovy) and Tiurinsaari (now Zapadnaya Beryozovy) and others of the archipelago’s apparently threatened areas. Reinforced patrols were also organised in the waters between Viipuri and Kotka by a naval force comprising as many as 100 Finnish and German vessels and craft based on or deployed to the islands and including two destroyers, five gunboats, five high-speed landing barges, 15 patrol vessels and up to 50 smaller craft.

On the night of 20 June, 10 patrol boats, seven minesweepers and 14 torpedo boats landed a reinforced infantry company from the 6^th Separate Marine Regiment on Nerva island some 10 miles (16 miles) to the west of the Koivisto archipelago, and found no Finnish opposition. This island had been selected as the launch point for further operations, and an all-round defensive perimeter was quickly created with field fortifications as well as a coastal battery of three 45-mm guns and six machine gun bunkers.

On the same night, there took place a naval action that was one of the few engagements in the Baltic Sea between larger surface ships of the German and Soviet navies. The German navy began its 'Drosselfang' undertaking in the area of Koivusaari and Piisaari area with the object of attacking Soviet smaller ships supporting the Soviet combined operation. The undertaking was deemed important enough for the commitment of two 'Elbing' class torpedo boats, namely T 30 and T 31 under the command of Kapitänleutnant Heinrich Peter-Pirkham.

No major Soviet warships were involved in the action as most of them were still blockaded in Leningrad, and the Soviet could therefore deploy in this area only four small gunboats, 10 patrol boats ('MO-4' class submarine chasers) and 14 motor torpedo boats. The two German torpedo boats shelled the Soviet craft but caused only damage to the gunboats MBK-503, MBK-505 and the submarine chaser MO-106 without sinking any of them. The Soviets counterattacked with their motor torpedo boats: the first attack was repelled with damage to TK-53, TK-63 and TK-153, while the second attack was another failure in which TK-101 and TK-103 were damaged. Finally, TK-37 and TK-60 delivered a pincer attack and launched their torpedoes simultaneously against T 31, which was hit and quickly sunk. Some 76 German sailors lost their lives, and another six were captured by Soviets. Finnish units rescued other German sailors (including 23 wounded, of whom two died). After the loss of her sister ship, T 30 retreated after suffering light damage and a few casualties (one sailor killed and another 13 wounded). The Germans claimed to have sunk a number of the Soviet motor torpedo boats, but while some were damaged, none was sunk.

(A month later, on 16 July, the Germans attempted a similar attack as 'Buckenwald', in which they committed the torpedo boats T-30, T-8 and T-10. The action took the form of a brief but inconclusive skirmish with the Soviet torpedo boat Tucha and the minesweepers Tszcz-211 Rym and Tszcz-217 Kontr-Admiral Yurkovsky. No damage resulted, but shortly before the engagement the Soviets had suffered damage to two small patrol boats.)

In an effort to regain Nerva island, which was seen as important, the Germans and Finns in the following days sent a detachment torpedo boats, minesweepers, gun-armed amphibious ferry craft to it. The Germans and Finns made no attempt a landing on Nerva, but the island was subjected to frequent bombardments.

On the morning of 21 June, the Soviets landed a reconnaissance group based on a marine company (126 men) on Piisaari (now Severny Beryozovy), the northernmost island of the Koivisto archipelago. The men were transported and landed by a Soviet force comprising eight tenders, one armoured gunboat, one patrol boat and three smoke launcher boats. During the approach to the island in the Borkozund Strait, the detachment was attacked by six Junkers Ju 88 bombers, whose efforts slightly damaged the patrol boat, and then came under fire by coastal artillery on the islands of Björkö and Tiurinsari, suffering slight damage to two tenders and one smoke launcher boat. All the Soviet craft were able continue the mission. At about 0.500, the landing party came ashore on the eastern coast of Piisaari and swiftly established a beach-head 875 yards (800 m) wide and 545 yards (500 m) deep. Eight marines were killed during the landing. Contrary to Soviet intelligence data, there were significant Finnish forces on the island, and the beach-head was attacked by three infantry companies. In order to support the landed men, the Soviets landed another company of marines and one gun in the beach-head during the afternoon. Thus the landing, conceived as a reconnaissance, had developed into a tactical one.

In response, the Germans and Finns sent a detachment of ships against the Soviet beach-head, which thus came under the fire of four German gun-armed landing craft and four Finnish torpedo boats. The Soviet armoured gunboat BK-505 entered the battle, and ground-attack aircraft were summoned as a matter of urgency. About 40 minutes after the shelling had begun, the German and Finnish craft were attacked from the air: one German gun-armed landing craft was sunk, and another damaged. The German and Finnish craft left the area, and a short time later one of the Finnish torpedo boat succumbed to air attack. However, before the end of the day, these ships twice more attempted to break through to the beach-head, but were repulsed by artillery fire, and direct hits were observed. During 21 June, the Baltic Fleet’s air arm flew 221 sorties to attack ships and the Finnish forces on the island.

The fighting for the island continued, and the Soviet transfer of reinforcements to Piisaari from Björkö was noticed. Rall had already planned the withdrawal of the landed force on the night of 22 June, but after receiving the report of the landing’s senior officer, who had been wounded and evacuated, about the stability of the beach-head, the admiral changed his mind and ordered the entire 260^th Marine Brigade (1,453 men and 14 pieces of artillery) to be landed on the island. Implemented while under fire, the reinforcement effort had been completed without loss by 15.00 on 22 June by three armoured gunboats and 16 tenders. At 17.00, the brigade launched a decisive attack, and by the break of day on 23 June the Soviets had secured the whole island.

Realising the threat to the archipelago’s garrison forces, the German and Finns during the night of 23 June began the evacuation of their forces. This was achieved quickly, but only with the loss of two transport vessels to Soviet air attack. On 23 June, Soviet troops landed on the islands of Björkö and Tiurinsaari, meeting only very limited resistance.

On 25 June, one Soviet platoon (56 men) was landed on the island of Tuppuransaari. The Finnish garrison hastily evacuated after a short skirmish, abandoning two guns and five machine guns. On 27 June, a group of 38 Soviet troops was landed on the island of Ruonti, and found that the Finns had already left.