Finnish reconquest of the Karelian Isthmus ( 1941 ) The Finnish reconquest of the Karelian Isthmus ( 1941 ) refers to a military campaign carried out by Finland in 1941 . It was part of what is commonly referred to as the Continuation War . Early in the war Finnish forces liberated the Karelian Isthmus . It had been ceded to the Soviet Union on March 13 , 1940 , in the Moscow Peace Treaty , which marked the end of the Winter War . Later , in the summer of 1944 , the Soviet Union reconquered the southern part of the isthmus in the Vyborg - Petrozavodsk Offensive . Initial setup of the forces . Between the Army of Karelia and Gulf of Finland there were three Finnish corps : II Corps ( 2 . D , 15 . D and 18 . D ) north of the Vuoksi River , V Corps ( 10 . D ) and IV Corps ( 4 . D , 12 . D and 8 . D ) defending the coast . On the Soviet side there were 19th Rifle Corps ( 142 . D , 115 . D ) , 50th Rifle Corps ( 43 . D , 123 . D ) , 10th Mechanised Corps ( 21 . Armored D , 24 . Arm . D . and 198 . Mech . D ) in reserve and the division - strength 22nd Karelian Fortified Region , which defended the coast . The Soviet X Mechanized Corps were transferred at the end of June from the Karelian Isthmus to the southwest of Leningrad to defend against advancing Germans but left 198 . D as the only reserve to Soviet forces . The Finnish V Corps were disbanded and 10 . D were attached first to IV Corps ( Lt . Gen . Karl Lennart Oesch ) and late July to II Corps ( MJ . Gen . Taavetti Laatikainen ) as a reserve . Both parties were first on the defensive , and only small , company or battalion size probing attacks were made by both sides to improve their own positions . The loss of reserves prompted the Soviets to retreat to more defensible lines at the northernmost part of the front and continued fortifying in depth , creating concrete and wooden strongpoints , digging trenches and laying minefields , although the Finns advanced to keep contact with the enemy . This situation continued until July 31 , when the Finnish offensive began . Advance to the Lake Ladoga . The Soviet fortification works had been concentrated near the river Vuoksi and along the roads , so the Finns concentrated their forces on narrow , deep breakthroughs over the roadless terrains which were supported by pioneers building temporary supply roads through the forests and over the swamps . The 18 . D ( Col . Pajari ) attacked through the forest against the northernmost section of the Soviet 115 . D and instead of following roads they secured a roadcrossing and advanced again over the forest to the next road where they did the same . The roadcrossings were occupied by stronger units , which had to defend against several armor supported Soviet counterattacks . During one of those counterattacks Private Vilho Rättö captured a Soviet AT gun and aiming through the barrel he managed to destroy four enemy tanks , earning him the first Mannerheim Cross granted to a private . Finally on August 4 , the Finns managed to encircle and capture the Ilmee road crossing , thus forcing the Soviets to abandon their prepared positions between Ilmee and the border . The main thrust of 15 . D ( Col . Hersalo ) was against the Soviet IR588 / 142 . D , and concentrated the thrust against only a two kilometer wide section , where most of the artillery was concentrated . After breaching the border fortifications , they advanced five kilometers through the forest before coming to the road thus bypassing Soviet defences , which were encircled and captured one by one by forces coming behind the leading elements . After six days advance 15 . D was only three kilometers from the Viipuri - Sortavala railroad and 15 km from the western corner of Lake Ladoga and close to encircling Soviet forces on its left side . The 2 . D ( Col . Blick ) decided to encircle two battalions of Soviet IR461 which were defending Tyrjä village by encircling the village from east and pushing the defenders to Lake Tyrjänjärvi by using IR7 / 2 . D while IR28 / 2 . D passed the village and advanced southwards . While supported by artillery the Soviets managed to hold on four days , before the encirclement was complete . Some of the men were able to escape through the forests , but most of them and all their heavy equipment were trapped to the village . Also the Finns suffered heavy casualties in the fighting and the IR7 received the nickname " Tyrjän rykmentti " ( Regiment of Tyrjä ) . The capture of Tyrjä opened road towards the Elisenvaara railway crossing and at August 5 the first Finnish units reached the Viipuri - Sortavala railroad . The commander of the Soviet 23rd Army , Lt . Gen . M . Gerasimov , ordered on August 4 that 198th Rifle Division cease its counterattack near Sortavala and move south to attack advancing 2 . D together with 142 . D . Meanwhile 115 . D and 43 . D should tie up the Finnish reserves . Unfortunately this wasn ' t sufficient and 115 . D retreated to river Helisevänjoki , where hills and a river formed good defensive positions against attacking 18 . D . The 18 . D advanced to the river Helisevänjoki and reached the Viipuri - Sortavala railroad at the Inkilä roadcrossing at August 8 . The 10 . D ( Col . Sihvo ) was ordered to advance between 15 . D and 18 . D and at August 6 they reached Viipuri Sortavala railroad . 10 . D continued attack towards the Käkisalmi - Hiitola railroad , but Soviet forces managed to keep the railroad and road open until August 8 , when 10 . D captured the village of Hiitola . When the first troops of 10 . D reached Lake Ladoga next day , the last land connection to Soviet troops defending the northwest coast of Lake Ladoga was severed . The Soviets tried to open the connection with strong counterattacks during August 10 and 11 but were unsuccessful . Meanwhile IR28 / 2 . D had captured the Elisenvaara railway junction on August 9 , thus opening supply routes through railways from Finland . After the battle of Tyrjä IR7 / 2 . D rested two days as a division reserve before continuing the attack along the railroad towards the town of Lahdenpohja , which it captured on August 8 , thus dividing Soviet forces in the forming bridgehead . At the same day , 2 . D was transferred to new I Corps with an order to clear northern Soviet bridgehead . It was left to 15 . D and 10 . D to clear southern bridgehead where Soviet 142 . D and 198 . D were ordered to withdraw to Kilpolansaari island for naval transport . This withdrawal was executed in an orderly fashion and Finns couldn ' t encircle any bigger enemy formations . At August 11 15 . D captured the Hiitola railway junction , and at August 13 all Soviet forces had retreated to the Huiskonniemi peninsula and the Kilpolansaari island . Having total air superiority , the Soviets managed to withdraw almost all the men and material from the bridgehead and at August 23 15 . D , which was left to press the Soviets , had cleared all remaining rearguards from the island . Crossing the River Vuoksi . The Soviet intention was to start a large counteroffensive on August 10 , and the 23rd Army had received 265 . D reinforcements to the Räisälä area . The offensive was to be directed against 18 . D and 10 . D , the objective being to open roads to encircled forces on northwest coast of Lake Ladoga . Coincidentally , the 18 . D had been resting and received order to continue advance on the same day , so when the Soviet attack started at Inkilä , Finns in turn started their own only 5 km westwards . While the Soviet attack failed to gain ground , Finnish attack managed to cut Soviets ' main supply route and subsequent Finnish counterattack forced Soviet forces to retreat southwards while fighting delaying action and first Finnish troops reached the Vuoksi River at August 14 at Antrea ( now Kamennogorsk ) , where they continued clearing the left shore of the river . Soviets started to move forces from southwestern side of Viipuri to defend Enso ( now Svetogorsk ) and to counterattack to Antrea at August 16 , but when the attack failed , the Soviets were forced to evacuate northern shore at August 21 . At the eastern side the Finns advanced southeastward and reached Vuosalmi at August 17 and northern outlet of river Vuoksi at August 18 . Immediately , the Finns crossed River Vuoksi unopposed a few kilometers west of Vuosalmi at August 17 , and by August 20 they had secured the beachhead . The Soviet counterattack against 10 . D started August 14 and it managed to push Finns 2 km northwards before Finnish reinforcements managed to stop it . The 10 . D left the coast of Lake Ladoga to IR36 / 15 . D and concentrated all of its forces against Soviet 265 . D at Räisälä ( now Melnikovo ) . At August 15 the 10 . D started its own attack in which it encircled Soviet defenders in Räisälä at August 17 and captured it next day . From there it continued cleaning the left bank of northern outlet of River Vuoksi . At August 19 IR43 / 10 . D continued attack southward and reached Lake Suvanto at August 21 . From there it continued eastward with IR1 / 10 . D . This threatened all Soviet forces north of Vuoksi with encirclement and they started retreating from Käkisalmi which was captured at August 21 . The attack continued southward and as only small border guard units were capable to delay attackers , the river Taipaleenjoki and the shore of Lake Ladoga was reached at August 23 , but the Finnish troops were unable to cross river on the move . Capture of Viipuri and motti of Porlampi . STAVKA recognized the serious situation , and ordered at August 20 to retreat to the new , unprepared defence line running from the southwest side of Viipuri northwards to river Vuoksi and along it to Lake Suvanto and through river Taipaleenjoki to Lake Ladoga . This decision shortened the frontline considerably , but it also meant abandoning defensive installations they had prepared last months along the border . The Finns were preparing to start their own attack along the southernmost stretch of the border at , so when they noticed the Soviets leaving their positions at August 21 , they were ordered to commence immediate pursuit . Although Soviet 43 . D ( MJ . Gen . V . Kirpitsnikov ) managed to man new positions north and west of Viipuri , they were unable to prevent Finnish 12 . D ( Col . Vihma ) to advance along the right bank of River Vuoksi and contact 18 . D , which was enlarging their beachhead at Vuosalmi , and at the evening of August 22 the whole right bank was in Finnish hands . Soviet 123 . D ( MJ . Gen . F . Aljabusev ) was defending the southwest side of Viipuri . Much of the troops of 123 . D and of 115 . D ( MJ . Gen . Konjkov ) which had retreated from upper Vuoksi were still unorganized due to fast retreat from their positions . The Finnish 4 . D ( Col . Viljanen ) advanced along the Saimaa Canal , pressing Soviet 43 . D from north . By August 23 the southernmost Finnish division , 8 . D ( Col . Winell ) , had cleared the western shore of the Bay of Viipuri up to the river Ykspäänjoki , and started to prepare the crossing of the bay . During August 23 , the Finns had managed to advance from the east to 8 km from Viipuri , but in the morning of August 24 Soviet 123 . D and 115 . D started a counteroffensive against Finnish forces east of Viipuri , probably trying to capture initiative and force Finns back to the northern side of River Vuoksi . Using heavy artillery fire , Soviets managed to push the defending Finns over 5 km backwards in places , but they didn ' t manage to create breaches to the front , and when the reserve of 12 . D , IR26 , which was already moving to the place for troop rotation , arrived , the Soviets were pushed back to their starting positions next day . The Soviet counterattack failed to affect the already - ordered attack by 12 . D , which severed the main railroad connection between Viipuri and Leningrad at August 25 . At the morning of August 24 , the Finnish 8 . D started crossing the Bay of Viipuri with the forces of III / IR45 to Lihaniemi Peninsula which it secured during the same day . At the next day they continued their attack and managed to sever last railroad running from Viipuri during afternoon , and managed to enlage their beachhead few kilometers to every direction during next two days . The 12 . D had continued their offensive southwest , and severed Viipuri - Leningrad main road at August 27 . At August 28 STAVKA allowed the 23 . Army to withdraw from Viipuri and form new a defensive line to approximately the same place where Mannerheim Line had been . The Soviet forces began immediate retreat and tried forcefully to open the roads . At Ylä - Somme they managed to open one road at the evening of August 28 , and during the night they managed to move several truck trains through , although under Finnish fire . The artillery fire caused several casualties , and little by little the road become more and more congested until finally only men on foot were able to pass . During the next two days , the Soviets tried repeatedly to open the railroad line along the bay of Viipuri , but at the late evening of August 30 IR3 / 12 . D reached the positions of the 8 . D . The motti of Porlampi was ended . As the Soviet attempts to open the encirclement during the next day failed and as Finnish encirclement tightened , they made a final attempt to save the men by abandoning all vehicles and trying to escape on foot through the forests . The ring was already too tight and only small groups managed to escape at this last night . In the next morning , demoralized troops started to surrender . 9 , 000 men surrendered and 7 , 000 were buried there , but almost 12 , 000 men had managed to escape before the ring closed . Also , the booty was abundant : 306 artillery pieces , 55 tanks , 673 trucks , almost 300 tractors and around 4 , 500 horses . Advance to the old border . Along the main road and railroad between Viipuri and Leningrad , the Soviet order to retreat and form a new defensive line along the old Mannerheim Line came too late , as the 12 . D at the same day captured Leipäsuo and continued advance southwest , towards Lake Kuolemanjärvi , and southeast , along the railroad . The Soviet defences at main road at Summa held , but the Finns encircled these defences by breaching the defences at Munasuo . The defending remains of Soviet 123 . D managed to hold Finnish advance only few places and continued withdrawing towards Leningrad . At the morning of August 30 12 . D cut the Koivisto - Leningrad railroad at Kuolemanjärvi and reached the Gulf of Finland during the same day . Also at Vammelsuu , 12 . D cut the railroad at the same evening , but failed to cut main road . The Gulf was reached also here in the next morning , and the attack continued east to Terijoki , which was captured August 31 and reached old border at the river Rajajoki next day . The encircled Soviet forces at Koivisto retreated to the islands and Soviet fleet transferred them to Leningrad . The last defenders of Koivisto were evacuated November 1 . At the left side of 12 . D from August 23 the 18 . D started attacking southeast between Lake Muolaanjärvi and Vuoksi . By August 26 , the first lake isthmuses had been breached . Meanwhile first units of 2 . D were relieving the forces of the 18 . D from the isthmus between Lake Kirkkojärvi and Lake Punnusjärvi and 10 . D those from Lake Punnusjärvi to the river Vuoksi . After the mottis at the northwestern shores of Lake Ladoga had been cleared , I Corps was moved to the river Vuoksi where it took 10 . D and 15 . D to its command . The 18 . D breached the second lake isthmuses August 27 and rested one day before continuing attack towards the Kivennapa ( now Pervomaiskoye ) road crossing which it captured August 29 . The attack continued towards the old border which was reached August 31 . Also the 2 . D reached the old border at August 31 . The 10 . D had more troubles as Soviet 198 . D had started its counterattack August 29 . The Finnish attack started to gain speed during August 30 , and also 15 . D joined the attack from the other side of the river Vuoksi . The Valkjärvi railroad endpoint was captured at August 31 and because of the threat of encirclement , the Soviet forces were ordered to withdraw from the souther side of the river Vuoksi behind the old border . 15 . D followed the retreating Soviets closely and by September 2 old border had been reached everywhere . German pressure to attack Leningrad and the end of offensive . At August 20 , General W . Erfurth notified Mannerheim that Field Marshal W . Wilhelm Keitel would send a letter describing where Finns were asked to attack Leningrad . Mannerheim explained practical difficulties of the proposal and presented the opposition of both the political and military leadership to this attack . The government had decided beforehand that Finland would not attack Leningrad , and only after the pressure of military leadership they accepted a small advance across the old border to capture better defensive positions . The social democrats especially opposed crossing the border . When Keitel ' s letter came , Ryti and Mannerheim together prepared a negative answer . On August 31 , Erfurth contacted Mannerheim again and proposed that Finns should cancel the attack to East Karelia and instead attack Leningrad . Ryti and Mannerheim again refused . On August 31 Mannerheim gave the order that the attack be stopped at the line from the mouth of the river Rajajoki to Ohta . The exact line between Ohta and Lake Ladoga would be ordered later , when the Finns had reached the old border there . That would shorten the frontline without the need to attack Soviet fortifications north of Leningrad ( KaUR ) . In this last phase , the Soviets had six infantry divisions and a number of separate battalions and regiments defending Leningrad from the north , but all of them were at half strength due to the hard fighting with the Finns . 12 . D had reached the target already on September 1 , but elsewhere the attack started on September 2 . 18 . D captured Mainila at the same day and Valkeasaari ( now Beloostrov ) at next day . By September 7 both 18 . D and 2 . D had reached their targets between River Rajajoki and Ohta . The commander of I Corps , Colonel Mäkinen , ordered his troops to advance to the line Ohta - Lake Lempaalanjärvi - Old border at Lake Ladoga with an addition , that if strong defences were met , the offensive could be stopped there . At September 4 the attack began , and at September 6 10 . D managed to encircle and destroy Soviet IR941 at Kirjasalo . Finally at September 9 the ordered line was reached everywhere and Finnish forces moved to the defensive . The Soviet military leadership quickly learned of lessened Finnish pressure , and already at September 5 two divisions were transferred from Karelian Isthmus to the south of the city , against the Germans . Although the Finnish troops on the Karelian Isthmus didn ' t actively participate in the Siege of Leningrad , merely just their existence contributed to the siege by hampering the supply of the city around and across the Lake Ladoga . Half of the Finnish part of the Isthmus was reconquered by the Soviet Union in the Fourth strategic offensive in 1944 .