The 'Continuation War', also known as the '2^nd Soviet-Finnish War', to the Finns as the 'Jatkosota' and to the Soviets as the 'Finnish Front of the Great Patriotic War', was fought between German-supported Finnish troops against the Soviet forces on the northern end of the Eastern Front (25 June 1941/19 September 1944).

Germany regarded its operations in the region as part of its overall war efforts on the Eastern Front and provided Finland with critical matériel support and direct military assistance, including economic aid.

The 'Continuation War' began 15 months after the end of the 'Winter War', known to the Finns as the 'Talvisota' and also fought between Finland and the USSR. Many reasons have been suggested for the Finnish decision to invade the USSR, the recapture of territory lost during the 'Winter War' being regarded as the most likely. Other justifications for the conflict included Finnish president Risto Ryti’s vision of a Greater Finland and the desire of the Finnish commander-in-chief, Sotamarsalkka C. G. E. Mannerheim, to annex East Karelia. Plans for the attack were developed jointly between the Wehrmacht and a faction of Finnish political and military leaders, with the rest of the government remaining ignorant. Despite the co-operation in the conflict, Finland never formally signed the Tri-Partite Pact, although it did sign the Anti-Comintern Pact. The Finnish leadership justified its alliance with Germany as self-defence, and Finland is generally regarded as a co-belligerent rather than as an ally of Germany.

On 22 June 1941, Germany launched its 'Barbarossa' invasion of the USSR, and three days later the USSR flew an air raid on Finnish cities, prompting Finland to declare war and to allow German troops stationed in Finland to begin offensive warfare. By September 1941, Finland had regained its post-'Winter War' territorial concessions to the USSR, namely the Karelian isthmus and Ladoga Karelia. However, the Finnish army continued the offensive past the 1939 border during the conquest of East Karelia, including Petrozavodsk, and halted only some 19 to 20 miles (30 to 32 km) from the centre of Leningrad. Finland then took part in the siege of the city by cutting the northern supply routes and by digging in until 1944.

In Lapland, joint German and Finnish forces failed to capture Murmansk or to cut the Kirov Railway linking this ice-free northern port with the rest of the USSR and thus a strategically important transit route for Lend-Lease equipment supplied to the USSR. The conflict stabilised with only minor skirmishes until the tide of the war turned against the Germans and the Soviet 'Vyborg-Petrozavodsk Strategic Offensive Operation' occurred in June 1944. The offensive drove the Finns from most of the territories that they had gained during the war, but the Finnish army halted the offensive in August 1944.

Hostilities between Finland and the USSR ended with a ceasefire on 5 September 1944, formalised by the signing of the Moscow Armistice on 19 September 1944. One of the conditions of this agreement was the expulsion, or disarming, of any German troops in Finnish territory, leading to the 'Lapland War' ('Lapinsota') between Finland and Germany.

Finland’s involvement in World War II was formally concluded by the signature of the Paris Peace Treaties in 1947. This confirmed the territorial provisions of the 1944 armistice: the restoration of borders as ordained in the 1940 Moscow Peace Treaty, the cession to the USSR of the Petsamo area on Finland’s northern coast, and the leasing to the USSR of the Porkkala peninsula on Finland’s south-western coast. Finland was also required to pay US$300 million in war reparations, accept partial responsibility for the war, and acknowledge that it had been a German ally. Soviet pressure also persuaded Finland to refuse Marshall Plan aid.

Casualties had totalled 63,200 Finns and 23,200 Germans dead or missing, and 158,000 Finns and 60,400 Germans wounded. Estimates of dead or missing Soviets range from 250,000 to 305,000, and 575,000 have been estimated to have been wounded or fallen sick.

On 23 August 1939, Germany and the USSR had signed the Molotov-Ribbentrop Pact in which both parties agreed to divide the independent countries of Finland, Estonia, Latvia, Lithuania, Poland and Romania into spheres of interest, with Finland falling within the Soviet sphere. One week later, Germany invaded Poland in 'Weiss' (i), leading to the UK and France to declare war on Germany on 3 September. In accord with a secret protocol in the pact, the USSR invaded eastern Poland on 17 September. Moscow also turned its attention to the Baltic states, demanding that they allow Soviet military bases to be established and troops to be stationed on their soil, and the governments of the three little Baltic stages acquiesced to these demands and signed agreements in September and October.

In October 1939, the USSR attempted to negotiate the cession by Finland of territory on the Karelian isthmus and in the islands of the Gulf of Finland, and to permit the establishment of a Soviet military base near Helsinki, the Finnish capital. The Finnish government refused, and Soviet forces invaded Finland on 30 November 1939 at the start of the 'Winter War'. The USSR was expelled from the League of Nations and was condemned by the international community for this aggression. Foreign support for Finland was promised, but there materialised very little physical help except from Sweden. The Moscow Peace Treaty concluded the 105-day 'Winter War' on 13 March 1940 and started the Interim Peace. By the terms of the treaty, Finland ceded 9% of its national territory and 13% of its economic capacity to the USSR. About 420,000 evacuees were resettled from the ceded territories as Finland avoided total conquest of the country and retained its sovereignty.

Before the war, Finnish foreign policy had been based on multilateral guarantees of support from the League of Nations and Nordic countries, but this policy was considered a failure. After the war, Finnish public opinion came swiftly to favour the reconquest of Finnish Karelia. The government declared national defence to be its first priority, and military expenditure rose to nearly half of public spending. Finland purchased and received donations of war matériel during and immediately after the 'Winter War', and the Finnish leadership worked to preserve the spirit of unanimity which had been felt throughout the country during the 'Winter War'.

The USSR had also received the Hanko naval base, on Finland’s southern coast to the west of Helsinki, and here deployed more than military personnel. Relations between Finland and the USSR remained strained after the signature of this one-sided peace treaty, and there were disputes regarding the implementation of treaty provisions. Finland sought security against further territorial depredations by the USSR and proposed mutual defence agreements with Norway and Sweden, but these initiatives were quashed by Moscow.

After the 'Winter War', Germany was initially viewed with distrust by the Finns as it was considered an ally of the USSR. Even so, the Finnish government sought to restore diplomatic relations with Germany, but at the same time continued its Western-orientated policy and negotiated a war trade agreement with the UK. The agreement was renounced after the German invasion of Denmark and Norway on 9 April 1940 led the UK to cut all trade and traffic communications with the Nordic countries. With the fall of France, a Western orientation was no longer considered a viable option in Finnish foreign policy. On 15/16 June, the USSR occupied the three Baltic states almost without resistance, and Soviet puppet régimes were installed. Within two months Estonia, Latvia and Lithuania had been incorporated into the USSR, and by the middle of 1940 the two remaining northern democracies, Finland and Sweden, were thus encircled by the hostile states of Germany and the USSR.

On 23 June, shortly after the beginning of the Soviet occupation of the Baltic states, the Soviet foreign minister, Vyacheslav Molotov, contacted the Finnish government to demand that a mining licence be issued to the USSR for the nickel mines in the area of Petsamo or, alternatively, permission be granted for the establishment of a joint Soviet/Finnish company to operate there. A licence to mine the deposit had already been granted to a British/Canadian company, so the demand was rejected by Finland. During the following month, the Soviets demanded that Finland destroy the fortifications on the Åland islands group in the mouth of the Gulf of Bothnia and grant the Soviets the right to use Finnish railways to transport Soviet troops to the newly acquired Soviet base at Hanko. The Finns very reluctantly agreed to these demands. On 24 July, Molotov accused the Finnish government of persecuting the communist Finland/Soviet Union Peace and Friendship Society, and soon after this publicly declared support for the group. The society organised demonstrations, some of which turned into riots.

Russian-language sources maintained that Soviet policies leading to the 'Continuation War' were best explained as defensive measures by offensive means. The Soviet division of occupied Poland with Germany, the Soviet annexation of Lithuania, Latvia and Estonia, and the Soviet invasion of Finland in the 'Winter War' have been described as elements in the Soviet construction of a security zone or buffer region from the perceived threat from the capitalist powers of Western Europe. Post-war Russian-language sources considered establishment of Soviet satellite states in the Warsaw Pact countries and the Finno-Soviet Treaty of 1948 as the culmination of the Soviet defence plan. Western historians have disputed this view and described pre-war Soviet policy as an attempt to stay out of World War II and regain land lost after the fall of the Russian empire.

On 31 July 1940, Adolf Hitler gave the order to plan an invasion of the USSR, and this required that Germany had to reassess its position regarding both Finland and Romania. Until that time, Germany had rejected Finnish appeals for the purchase of weapons, but with the prospect of an invasion of the USSR that policy was reversed, and in August the secret sale of weapons to Finland was permitted. Military authorities signed an agreement on 12 September, and an official exchange of diplomatic notes took place on 22 September. Meanwhile, German troops were allowed to transit through Sweden and Finland. This was a change in policy that meant Germany had effectively redrawn the border of the German and Soviet spheres of influence in violation of the Molotov-Ribbentrop Pact.

In response to that new situation, Molotov visited Berlin on 12/13 November 1940 and requested that Germany withdraw its troops from Finland and stop enabling Finnish anti-Soviet sentiments. He also reminded the Germans of the 1939 pact. Hitler inquired how the Soviets planned to settle the 'Finnish question', to which Molotov responded that it would mirror the events in Bessarabia and the Baltic states. Hitler rejected that course of action. In December, the USSR, Germany and the UK all voiced opinions concerning the suitability of the Finnish presidential candidates: Risto Ryti was the sole candidate who received no objection by any of the three powers, and was elected on 19 December.

In January 1941, Moscow demanded that Finland relinquish control of the Petsamo mining area to the Soviets but, emboldened by a rebuilt defence force and German support, Finland rejected the proposition. On 18 December 1940, Hitler had officially approved 'Barbarossa', paving the way for the German invasion of the USSR, in which he expected both Finland and Romania to participate. Meanwhile, the Finnish liaison officer with the German army, Kenraalimajuri Paavo Talvela, met Generaloberst Franz Halder and Reichsmarschall Hermann Göring in Berlin, and for the first time advised the Finnish government, in carefully couched diplomatic terms, that they were preparing for war with the USSR. Outlines of the actual plan were revealed in January 1941 and regular contact between Finnish and German military leaders began in February.

In the late spring of 1941, the USSR made a number of goodwill gestures designed to prevent Finland from falling completely under German influence. Ambassador Ivan Zotov was replaced with the more flexible Pavel Orlov. Furthermore, the Soviet government announced that it no longer opposed a rapprochement between Finland and Sweden. Those conciliatory measures, however, had no effect on Finnish policy. Finland wished to re-enter the war mainly because of the Soviet invasion of Finland during the 'Winter War', which had taken place after Finnish intentions of relying on the League of Nations and Nordic neutrality to avoid conflicts had failed for lack of any outside support. Finland aimed primarily to reverse its territorial losses in the Moscow Peace Treaty and, depending on the success of the German invasion of the USSR and possibly to expand its borders, especially into East Karelia. Some right-wing groups, such as the Academic Karelia Society, supported a Greater Finland ideology.

The matter of when and why Finland prepared for war is still somewhat opaque. It is probable that the inner circle of the Finnish leadership, led by Ryti and Mannerheim, actively planned joint operations with Germany under a veil of ambiguous neutrality and without formal agreements after an alliance with Sweden had proved fruitless. The so-called 'driftwood theory', that Finland had been merely a piece of driftwood that was swept uncontrollably in the rapids of great power politics, seems improbable. Even then, most historians conclude that Finland had no realistic alternative to co-operation with Germany. On 20 May, the Germans invited a number of Finnish officers to discuss the co-ordination of 'Barbarossa'. The participants met on 25/28 May in Salzburg and Berlin, and continued their meeting in Helsinki on 3/6 June. They agreed upon the arrival of German troops, Finnish mobilisation and a general division of operations. They also agreed that the Finnish army would start mobilisation on 15 June, but the Germans did not reveal the actual date of the assault. The Finnish decisions were made by the inner circle of political and military leaders, without the knowledge of the rest of the government, which were not informed until 9 June that mobilisation of reservists, because of tensions between Germany and the USSR, would be required.

Finland never signed the Tri-Partite Pact, though it did sign the less formal Anti-Comintern Pact, which the German leadership saw as a 'litmus test of loyalty'. The Finnish leadership stated that Finland would fight against the Soviets only to the extent needed to redress the balance of the 1940 treaty, though some historians consider that it had wider territorial goals under the slogan 'shorter borders, longer peace'. During the war, the Finnish leadership generally referred to the Germans as 'brothers in arms' but also denied that they were allies of Germany, instead claiming to be 'co-belligerents'. For Hitler, the distinction was irrelevant as he saw Finland as an ally. The 1947 Paris Peace Treaty signed by Finland described Finland as having been 'an ally of Hitlerite Germany' during the 'Continuation War'. In a 2008 poll of 28 Finnish historians, 16 said that Finland had been an ally of Germany, six said it had not, and six adopted no position.

The Northern Front of the Leningrad Military District was commanded by General Leytenant Markian M. Popov and numbered around 450,000 soldiers in 18 divisions and 40 independent battalions in the Finnish region. During the Interim Peace, the Soviet military had revised its operational plans for a conquest of Finland, but with the start of 'Barbarossa' on 22 June 1941, the Soviets required their best units and latest matériel to be deployed against the Germans and so abandoned plans for a renewed offensive against Finland. The 23^rd Army was deployed in the Karelian Isthmus, the 7^th Army in Ladoga Karelia and the 14^th Army in the Murmansk and Salla area of Lapland. The Northern Front also commanded eight aviation divisions. As the initial German strike against the Soviet air forces had not affected those located near Finland, the Northern Front could deploy about 700 aircraft supported by a number of wings of the Soviet naval aviation arm. The Red Banner Baltic Fleet comprised two battleships, two light cruisers, 47 destroyers or large torpedo boats, 75 submarines, more than 200 smaller craft, and hundreds of aircraft. As such, it outnumbered the Kriegsmarine.

The Finnish army mobilised between 475,000 and 500,000 men in 14 divisions and three brigades for the invasion, under the command of Mannerheim. The army was organised as follows: the II Armeijakunta (corps) and IV Armeijakunta were deployed to the Karelian isthmus and comprised seven infantry divisions and one brigade; the Karjalan Armeija (Army of Karelia] was deployed to the north of Lake Ladoga under the command of Kenraliluutnantti Erik Heinrichs and comprised the VI Armeijakunta, the VII Armeijakunta and the Ryhmä 'Oinonen' (Oinonen group) with a total of seven divisions, including Generalleutnant Erwin Engelbrecht’s German 163^rd Division, and three prikaati (brigades); and the 14^th Divisioona deployed in the Kainuu region and under the direct command of the Finnish headquarters (Päämaja).

Although initially deployed for static defence, the Finnish army was to later launch an attack to the south on each side of Lake Ladoga, putting pressure on Leningrad and thus supporting the advance of Generalfeldmarschall Wilhelm Ritter von Leeb’s Heeresgruppe 'Nord' from the south-west. Finnish intelligence had overestimated the strength of the Soviet army, when in fact it was numerically inferior to Finnish forces at various points along the border. The Finnish army, and especially its artillery, was stronger than it had been during the 'Winter War' but included only one armoured battalion and had a general lack of motorised transport. The Finnish air force had 235 aircraft in July 1941 and 384 by September 1944, despite losses. Even with the increase in aircraft, the air force was constantly outnumbered by those of the Soviets.

Generaloberst Nikolaus von Falkenhorst’s Armee 'Norwegen', comprising four divisions totalting 67,000 German soldiers, held the Arctic front, which stretched approximately 310 miles (500 km) through Finnish Lapland. This army would also be tasked with taking Murmansk and the Kirov Railway during 'Silberfuchs'. The Armee 'Norwegen' was under the direct supervision of the Oberkommando des Heeres, and was organised into General Eduard Dietl’s Gebirgskorps 'Norwegen' and Generalleutnant Karl Weisenberger’s XXXVI Gebirgskorps with Kenraalimajuri Hjalmar Siilasvuo’s Finnish III Armeijakunta and Eversti Erkki Raappana’s 14^th Divisioona attached to it. The Oberkommando der Luftwaffe assigned 60 aircraft from Generaloberst Hans-Jürgen Stumpff’s Luftflotte V to provide air support to the Armee 'Norwegen' and the Finnish army, in addition to its main responsibility of defending Norwegian air space. By contrast with the front in Finland, a total of 149 divisions and 3,050,000 men were deployed for 'Barbarossa'.

During the evening of 21 June 1941, German minelayers hiding in the Archipelago Sea (that part of the Baltic Sea between the Gulf of Bothnia, the Gulf of Finland and the Sea of Åland within Finnish territorial waters) laid two large minefields across the Gulf of Finland. Later that night, German bombers flew along the Gulf of Finland to Leningrad, mining the harbour and the Neva river, making a refuelling stop at Utti in Finland on the return leg. In the early hours of 22 June, Finnish forces launched 'Kilpapurjehdus', deploying troops in the demilitarised Åland islands group. Although the 1921 Åland convention (between Sweden, Finland, Germany, the UK, France, Italy, Denmark, Poland, Estonia and Latvia) included clauses allowing Finland to defend the islands only in the event of an attack, the co-ordination of this operation with the German invasion and the arrest of the Soviet consulate staff stationed on the islands meant that the deployment was a deliberate violation of the treaty.

On the morning of 22 June Hitler proclaimed that 'Together with their Finnish comrades in arms the heroes from Narvik stand at the edge of the Arctic Ocean. German troops under command of the conqueror of Norway, and the Finnish freedom fighters under their Marshal’s command, are protecting Finnish territory.'

Following the launch of 'Barbarossa' at about 03.15 on 22 June 1941, the USSR despatched seven bombers on a retaliatory air raid into Finland, hitting targets at 06.06. as reported by the Finnish coast-defence ship Väinämöinen. On the morning of 25 June, the USSR launched a larger air offensive, with 460 fighters and bombers targeting 19 airfields in Finland, though inaccurate intelligence and poor bombing accuracy resulted in several raids hitting Finnish cities or towns, and causing considerable damage. Some 23 Soviet bombers were lost in this attack, while the Finnish forces lost no aircraft. Although the USSR claimed that the air attacks were directed against German targets, particularly airfields, in Finland, the Finnish government used the attacks as justification for the approval of a 'defensive war'.

The Finnish plans for the offensive in Ladoga Karelia, round the northern end of Lake Ladoga, were finalised on 28 June, and the operation’s first stage began on 10 July. At the start of the 'Continuation War' the Finnish army was deployed in a defensive posture, but on 29 June Mannerheim created the Karjalan Armeija under the command of Heinrichs and with instructions to prepare to attack Ladoga Karelia. The Karjalan Armeija comprised Kenraalimajuri Paavo Talvela’s VI Armeijakunta (the 5^th Divisioona and 11^th Divisioona), Kenraalimajuri Woldemar Hägglund’s VII Armeijakuna (the 7^th Divisionna and 19^th Divisioona) and Kenraalimajuri Woldemar Oinonen’s Ryhmä 'Oinonen' (also known as the Ryhmä 'O'), the Ratsuväkiprikaati or cavalry brigade, and the 1^st Jääkäriprikaati and 2^nd Jääkäriprikaati). Eversti Paavo Paalu’s 1^st Divisioona was kept in reserve. The Finns planned to separate the defending Soviet forces by reaching the shore of Lake Ladoga and then advancing along the lake’s shores.

Opposing the Finnish forces were General Leytenant Filipp D. Gorelenko’s 7^th Army with the 168^th Division near Sortavala and the 71^st Division to the north of the Jänisjärvi lake. The Soviets had prepared field fortifications along the border across Sortavala and at the important road crossings at Värtsilä and Korpiselkä.

It was on 9 July that the order for the offensive to start. The Finns' main task of breaking through the Soviet defences between Värtsilä and Korpiselkä was given to Talvela’s VI Armeijakunta. The Finnish offensive quickly overwhelmed the Soviet defenders. Eversti Ruben Lagus’s 1^st Jääkäriprikaati was brought from the Ryhmä 'Oinonen' to spearhead the assault, and this created a gap in the Soviet defences through which Finnish light infantry, some mounted on bicycles, drove forward.

The right flank of the Finnish offensive, based on the 11^th Divisioona of the VI Armeijakunta, encountered strong Soviet resistance on the eastern shore of the Jänisjärvi lake, and the task of clearing the resistance lasted until 16 July. After clearing the resistance, the 11^th Division advanced, rounded the southern end of the Jänisjärvi lake and established westward-facing positions along the Jänisjoki river. Simultaneously, the VII Armeijakunta had been attacking southward on the western side of the Jänisjärvi lake; however, the strength of the Soviet defensive effort turned the offensive into a crawl, and it took until 15 July for the Finnish forces to reach the main Soviet defences. It took until 17 July ore the VII Armeijakunta to reach the Jänisjoki river, and the clearance of the surrounded Soviet forces lasted to 21 July. As the Finnish advance had extended the front line, some of the Finnish forces were starting to redeploy on 16 July, with the 1^st Divisioona ordered to cover the eastern flank of the advance, while Eversti Aarne Snellman’s 17^th Divisioona, which had left the pinning of the Soviet base at Hanko to local troops, was also brought into the area. The two-regiment German 163^rd Division was ordered to capture the town and railroad junction of Suvilahti. These redeployments had effectively increased the Finnish strength in the area by three divisions.

The Finnish advance on the left flank of the VI Armeijakunta by the two-brigade Ryhmä 'Oinonen' stalled almost as soon as it had started. Its advance tied down some Soviet troops but Talvela, commander of the VI Armeijakunta, assessed that the mission of the Ryhmä 'Oinonen' had been a failure. However, Talvela also criticised his superior’s orders to use these lighter troops against Soviet positions which were known to be strong.

The main Finnish advance continued to the south in the direction of Loimola, through which ran the railway linking Sortavala and Petrozavodsk. Loimola had been taken by the Finnish forces by 15 July, and Talvela pressed his forces farther and Lagus’s 1^st Jääkäriprikaati finished its 68-mile (110-km) opposed advance when it reached the shore of Lake Ladoga at Koirinoja on the following day, thereby severing the connections between the Soviet forces in the area. While Talvela continued his advance both farther to the east along the shore of Lake Ladoga and farther inland, the Soviets had reorganised some of their forces and were rushing reinforcements to Lake Ladoga’s eastern shore. The 452^nd Motorised Regiment set up defensive positions around the town of Salmi, but the Finnish forces encircled the defenders and had captured Salmi by 21 July. After the VI Armeijakunta reached the 1939 border on 23 July, on the next day Mannerheim called a halt to advances farther to the east and ordered the preparation of defensive positions along the Tuulema river. Crossing of the 1939 border did not sit well with all of the Finnish troops, and more than 2,000 men initially refused to cross the old border.

Eversti Antero Svensson’s 7^th Divisioona of the VII Armeijakunta launched its attack toward Sortavala from the east and managed to capture the village of Ruskeala on 25 July, which made it possible for the Finns to present a unified front against the Soviet forces defending Sortavala. The Soviets had in turn reinforced their defending 168^th Division in the area with the 198^th Motorised Division and prepared to launch a counterattack toward the Jänisjoki river. The Finns captured the plans of the Soviet counterattack, however, and with fresh Finnish troops available to meet the Soviet advance, the counterattack failed and by 1 August the 198^th Motorised Division was in full retreat. The Finnish decision to order Kenraalimajuri Taavetti Laatikainen’s II Armeijakunta to advance trapped the Soviet forces.

By 7 August, Eversti Aarne Blick’s 2^nd Divisioona of the II Armeijakunta had reached the shore of Lake Ladoga at Lahdenpohja and cut off the Soviet divisions operating to the north-west of Lake Ladoga from their intended withdrawal routes. Near Sortavala the attacking Finnish forces of the 2^nd Divisioona, 7^th Divisioona and 19^th Divisioona were reorganised on 8 August into Eversti Einar Mäkinen’s I Armeijakunta and the town fell to the Finnish forces on 15 August. The defending Soviet forces of the 168^th Division pulled back along the shore but were encircled in a motti (pocket). The Soviets then managed to evacuate most of their men on barges over Lake Ladoga, but the Finns captured large amounts of matériel that the Soviets were unable to evacuate.

Farther to the south, the Finnish invasion of the Karelian isthmus was undertaken by two corps. Laatikainen’s II Armeijakunta was to the north of the Vuoksi river and Kenraaliluutnantti Karl Lennart Oesch’s IV Armeijakunta to the south of this river. The II Armeijakunta now comprised Eversti Jussi Sihvo’s 10^th Divisioona, Eversti Niilo Hersalo’s 15^th Divisioona and Eversti Aaro Pajari’s 18^th Divisioona, the 10^th Divisioona having been added after the II Armeijakunta had been forced to divert its 2^nd Divisioona to operations in Ladoga Karelia. The IV Armeijakunta comprised two divisions and one reinforced regiment on its front (Eversti Claes Winell’s 8^th Divisioona, Eversti Einar Vihma’s 12^th Divisioona and Everstiluutnantti Lauri Pallari’s Jalkaväkirykmentti, together with Eversti Kaarlo Viljanen’s 4^th Divisioona in reserve.

As the Finnish operation started, the defending Soviet forces consisted nominally of the XIX Corps and L Corps. The XIX Corps comprised the 115^th and 142^nd Infantry Divisions, the 198^th Motorised Division) and the 14^th Motorised Regiment. The 198^th Motorised Division was tied down in fighting near Sortavala, and the two other divisions occupied positions close to the border. The 265^th Division was en route to the sector to act as the corps' reserve. The relatively quietness of the front had prompted the Soviet leadership to transfer the command elements of the L Corps into an area to the south of Leningrad on 21 July, leaving its 43^rd Division and 123^rd Division under the direct command of General Leytenant Piotr S. Pshennikov’s 23^rd Army.

The II Armeijakunta's advance started on 31 July. The Soviet defences slowed the Finnish advance, which was in itself hampered by the Finnish tactic of advancing through forest, which caused severe logistical problems. By 14 August the 18^th Divisioona had captured the town and crossing point of Antrea, which left the 115^th Division separated from the rest of the XIX Corps. Advancing in terrain that had almost no useful roads also slowed the 15^th Divisioona's advance, and the formation managed to take Hiitola only on 11 August after the 10^th Divisioona had also been deployed to the front. The Finnish victory at Hiitola forced the 142^nd Division and 198^th Motorised Division to withdraw onto Kilpola island in the north-western part of Lake Ladoga, where they were penned into a motti against the shore of Lake Ladoga. The Finns had cleared the motti by 23 August, but by then the Soviets had already evacuated 26,000 of their men across Lake Ladoga.

Soiiet control of the Karelian Isthmus near Lake Ladoga was crumbling after the defeat of these two Soviet divisions. Sihvo’s 10^th Divisioona came across the newly arrived 265^th Division on 15 August, and after a sharp engagement encircled the remnants of the Soviet division, of which a small part managed to escape two days later. By that time the division’s casualties already amounted to 234 men killed, 1,155 wounded and 4,830 missing in action. These successes allowed the Finnish forces to act more freely, and they captured the remains of the town of Käkisalmi on 21 August and the village of Taipale on 23 August. Pajari’s 18^th Divisioona started to cross the Vuoksi river on 17 August and the formation had soon created a solid bridgehead.

The main objective for the IV Armeijakunta, on the Finnish right flank, was the city of Viipuri, and the plan called for the encirclement and swift seizure of the town. However, the Finnish general headquarters did not allow the IV Armeijakunta to launch its active pursuit of the Soviet forces until 21 August. By this time the 43^rd Division and 123^rd Division had already started to pull back from their exposed positions close to the border, while the 115^th Division was racing to contain the Finnish crossing of the Vuoksi river. This meant that the Finnish plan of tying down the Soviets had failed before it could even have been put to action. However, the crossing of the Vuoksi river by the 18^th Divisioona was assisted by Vihma’s 12^th Divisioona and Eversti Matti Tiiainen’s Kevyt Prikaati 'T' (Light Brigade 'T'), which comprised the 1^st Jääkäripataljoona (light infantry battalion), two light detachments and two artillery companies) of the IV Armeijakunta and punched through the Soviet line.

The Soviet withdrawal to the narrow part of the Karelian isthmus allowed the Soviets to concentrate more effectively and thus bring their numbers to bear. The 115^th Division and 123^rd Division were tasked with driving the Finns back across the Vuoksi river, and their attack started on 24 August. The Soviet attack hit the Kevyt Prikaati 'T' and forced the Finns either to retreat or to dig in. As a result, the Finnish brigade was immobilised and partially surrounded. On 25 August a chance shell detonation artillery strike killed Tiiainen, who was succeeded in command by Everstiluutnantti Valter Nordgren two days later, but then the Finnish forces relieving the Kevyt Prikaati 'T' turned back the attack and forced the Soviet divisions to retreat. The IV Armeijakunta proceeded to cut the routes to the south from Viipuri, and on 24 August Winell’s 8^th Divisioona crossed Viipuri Bay and cut the coastal route from Viipuri. By 28 August the 43^rd Division, 115^th Division and 123^rd Division had been encircled in the 'Battle of Porlammi' and compressed into a motti around the villages of Sommee and Porlampi.

The Finns had cut all the roads to the motti, but were unable to form a tight blockade in the thick forests, which allowed the majority of the men of the 115^th Division and 123^rd Division to escape towards Koivisto. However, the bulk of the 43^rd Division was destroyed at the 'Battle of Porlammi' on 1 September. The Finns' force advanced to the village and port of Koivisto on 2 September, but did not pursue the remnants of the Soviet divisions which had fled to the surrounding archipelago and in November evacuated by the Soviets. While the fighting near Viipuri was still continuing, the Finnish advance toward Leningrad progressed. The IV Armeijakunta was to advance along the western shore, the II Armeijakunta in the centre and Eversti Einar Mäkinen’s newly arrived I Armeijakunta along the eastern side of the isthmus. Mannerheim ordered the Finnish advance to halt just short of the Soviet fortifications. The Finnish forces reached the old border on 31 August and early in September approached the Soviet fortifications and stopped their advance.

On 20 August, General Waldemar Erfurth, the senior German liaison officer at the Finnish headquarters, notified Mannerheim that Generalfeldmarschall Wilhelm Keitel, the chief of the Oberkommando der Wehrmacht, was to send a letter describing where the Finns would be asked to attack Leningrad. Mannerheim explained the practical difficulties of the proposal and presented the opposition of Finland’s political and military leadership to this attack. The government had already decided that Finland would not attack Leningrad, and it was only after pressure from the military leadership that they accepted a small advance across the old border to capture better defensive positions. The Social Democrats in particular were opposed to any crossing of the border. When Keitel’s letter arrived, Ryti and Mannerheim together prepared a negative answer. On 31 August, Erfurth contacted Mannerheim again and proposed that the Finns should cancel their attack into East Karelia and instead attack Leningrad. Ryti and Mannerheim again refused. On 31 August Mannerheim gave the order that the attack be stopped on a line between the mouth of the Rajajoki river and Ohta. The exact line between Ohta and Lake Ladoga was to be decided later, after the Finns had reached the old border in that sector. This would shorten the front without the need to attack Soviet fortifications of the 22^nd Karelian Fortified Region to the north of Leningrad.

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 as a result of the severity of the fighting with the Finns.

The 12^th Divisioona had reached the target area on 1 September, but elsewhere the attack started only on 2 September. The 18^th Divisioona captured Mainila on the first day and Valkeasaari on the following day. By 7 September both the 18^th Divisioona and the 2^nd Divisioona had reached their targets between the Rajajoki river and Ohta. Mäkinen, the commander of the I Armeijakunta, ordered his troops to advance to the line linking Ohta, the Lempaalanjärvi lake and the old border at Lake Ladoga, but added that if strong defences were encountered the offensive could be stopped there. On 4 September the attack began, and on 6 September the 10^th Divisioona encircled and destroyed the 941^st Regiment at Kirjasalo. Finally, on 9 September the objective line was reached everywhere and Finnish forces switched to the defensive.

The Soviet military leadership quickly learned of lessened Finnish pressure, and on 5 September two divisions were transferred from the Karelian isthmus to the south of Leningrad to operate against the Germans. Although the Finnish troops on the Karelian isthmus had no active participation in the siege of Leningrad, their presence contributed to the siege by hampering the supply of the city around and across Lake Ladoga.

The third and most northerly of the Finnish operations in 1941 was the invasion of East Karelia. For more than one month after the outbreak of the 'Continuation War', Heinrichs’s Karjalan Armeija had been reinforced and readied itself to resume its earlier offensive while awaiting the recapture of the Karelian isthmus. The Soviets had prepared fortifications and brought more troops to the front. When the encirclements on the western shore of Lake Ladoga had been resolved, Eversti Antero Svensson’s 7^th Divisioona was transferred to the junction of the VI Armeijakunta and VII Armeijakunta.

Eversti Erkii Raappana’s 14^th Divisioona, which was operating under the direct command of the Finnish general headquarters, started its advance on 4 July. This formation was the northernmost Finnish element to the south of the demarcation line between the Finnish and German forces, and was opposed by elements of the 54^th Division. The division encircled and mauled the defending 337^th Regiment at Omelia and advanced toward its targets, Rukajärvi and the Ontajoki river until ordered to halt on 17 September after reaching its goals.

While the earlier offensive in Ladoga Karelia by the VI Armeijakunta had been successful, the same could not be said of all Finnish undertakings. The advance of the Ryhmä 'Oinonen' had bogged down almost immediately, and the VII Armeijakunta had been completely occupied in clearing the encircled Soviet forces from the Sortavala area. While the Finnish command had stopped the offensive, that did not prevent local commanders from preparing for further attacks. This meant repairing roads and railway tracks leading to the front line, and the left flank of the Karjalan Armeija also received permission to capture tactical jumping-off positions.

Th Ryhmä 'Oinonen' and Eversti Kaarlo Heiskanen’s 11^th Divisioona of Kenraalimajuri Woldemar Hägglund’s VII Armeijakunta were ordered to capture the region of Suvilahti and Suojärvi, and launched their attack on 19 August. The attack had driven the Soviet 71^st Division into a withdrawal by 21 August, and the Finns pressed forward to take the village of Tsalkki and its crossroads on 23 August. The Finns increased the pressure and advanced to reach the eastern edge of the Säämäjärvi lake on 1 September.

The Finnish plan for the offensive that was to begin on 4 September was based on Talvela’s VI Armeijakunta advancing from its current positions near Lake Ladoga to the south-east to reach the Svir river, linking Lakes Onega and Ladoga, and Hägglund’s VII Armeijakunta first taking the important crossroads of Prääsä and then continuing to Petrozavodsk. This offensive was believed to offer greater difficulty than the previous Finnish offensives asa result of the relative unfamiliarity of the terrain, the advance’s wide front and the expectation of Soviet reinforcements being despatched to protect the Murmansk railway.

The Finnish forces thus comprised elements of Heinrichs’s Karjalan Armeija. Farthest to the south was Talvela’s VI Armeijakunta with the 5^th Divisioona and 17^th Divisioona on the front and Lagus’s Ryhmä 'Lagus' with Lagus’s own 1^st Jääkäriprikaati and elements of the 5^th Divisioona as the mobile reserve. In the centre the Finns had Hägglund’s VII Armeijakunta initially with the 1^st Divisioona and 11^th Divisioona but soon reinforced with the 7^th Divisioona. Farther to the north was Oinonen’s Ryhmä 'Oinonen' together with Engelbrecht’s German 163^rd Division. Farthest to the north was Everstiluutnantti Eero Kuussaari’s Ryhmä 'Kuussari', a unit of about brigade strength.

The Soviet forces comprised Gorelenko’s 7^th Army, which had been split into two operational groups: the 'Olonets' Operational Group was located to the south and the 'Petrozavodsk' Operational Group in the centre. The 'Olonets' Operational Group comprised the recently formed 3^rd Militia Division with the 3^rd Naval Brigade in reserve, but was soon reinforced with the 314^th Division. The 'Petrozavodsk' Operational Group comprised the 272^nd Division with the 313^th Division in reserve. The 71^st Division defended the area farther to the north.

The Finnish offensive began in the early hours of 4 September at Tuloksa, when the largest artillery barrage so far in Finnish military history was unleashed. The 5^th Divisioona quickly broke through the Soviet defences and crossed the Tuloksa river. Once engineers had hastily built a pontoon bridge, the mechanised Ryhmä 'Lagus' crossed and raced to the east. The defending Soviet forces, consisting of the 3^rd Naval Brigade and supporting infantry regiments were forced, to either retreat or be encircled by the advancing Finnish forces. Ryhmä 'Lagus' used the mobility provided by its usage of motor vehicles and had captured Olonets by 5 September. Soviet attempts to re-form for the defence were hindered by the fact that most of their forces now consisted only of disorganised units.

The 5^th Divisioona and 17^th Divisioona also started their offensive towards the village of Nurmoila ,which was defended by the 3^rd Militia Division. By attacking from both south and north, the Finns forced the defending Soviets to withdraw toward the east despite the field fortifications the Soviets had constructed in the area. The Soviet withdrawal prevented Finns from closing the trap they had prepared for the Soviets, however, and on 7 September a strong infantry contingent together with the headquarters of the rd Militia Division managed to escape via forest paths, although without any of their heavy equipment.

The advance of the Ryhmä 'Lagus' reached the Svir river by 7 September near the town of Lodeynoye Pole. On the same day a detachment of the 17^th Divisioona cut the Murmansk railway. The Finns pressed forward and captured the railway bridge over the Svir river at Svirstroy on 13 September. By 22 September the VI Armeijakunta had advanced to the south of the Svir river, capturing Podporozhye in the process, and taken up a defensive posture. The Finnish bridgehead was at this point approximately 25 miles (40 km) wide and between 3.1 and 6.2 miles (5 and 10 km) deep. The 5^th Divisioona took position on the northern bank of the Svir river extending as far as this river’s mouth, while the 17^th Divisioona held the bridgehead in the area to the south of the Svir river.

The 11^th Divisioona's advance toward Pryazha (Prääsä in Finnish) encountered strong Soviet resistance but was able to progress through the local forests and encircle the defending Soviets. The advance was slow, however, and it was 5 September before the road to Petrozavodsk was cut by the Finnish forces. Encircled Soviet units made repeated counterattacks against the Finnish roadblock but failed to clear it. Steadily advancing, the 11^th Divisioona took Pryazha on 8 September. Meanwhile, the 1^st Divisioona advanced toward the village of Pyhäjärvi directly to the south of Pryazha. By 16 September the 1^st Divisioona had reached the southern end of Pyhäjärvi while the 7^th Divisioona had flanked the defending Soviet forces and reached their rear. After suffering heavy casualties, the surrounded Soviet forces escaped through the forest after abandoning their heavy equipment. The 11^th Divisioona continued its advance first to Polovina on 24 September, and thence to the crossroads at Vilga on 28 September, just 3.7 miles (6 km) from the suburbs of Petrozavodsk.

The Soviets realised at an early point that that holding Petrozavodsk against the Finnish forces advancing on the town from both the west and the south would require a costly effort. In an attempt to do that, therefore, the Soviets formed several new formations from NKVD units, broken or separated army units, and reinforcements. These new forces included the 37^th Division and the 1^st Light Infantry Brigade.

The Finns also brought in reinforcements, in the form of Eversti Kaarlo Viljanen’s 4^th Divisioona, which was ordered to advance along the road the Syamozero lake toward Petrozavodsk. By 14 September the division had already met fierce Soviet resistance, but the numerically superior Finnish forces managed to encircle and defeat the 313^th Division, which had no option but to retreat after suffering heavy casualties. However, the clearance of the last mottis took until 26 September. Elements of the 4^th Divisioona continued their advance with the object of cutting the road to the north from Petrozavodsk. The Finns captured the village of Markkila on 19 September, but could not break through the 313^th Division’s defence at Besovets (Viitana in Finnish) despite repeated attempts. While the 4^th Divisioona was unable to complete its mission of cutting off the Soviet forces defending the Petrozavodsk region, it did pin considerable Soviet forces and protected the only vulnerable flank of the Finnish advance.

The Ryhmä 'Lagus' had been advancing to the north-east from the Svir river, but its progress was slower than had been expected as a result of the heavy autumn rains, which turned the roads into quagmires of cloying mud. By September the advance had reached the village of Ladva, where the Ryhmä 'Lagus' met the 7^th Divisioona, and together the Finnish units encircled and then defeated the defending 3^rd Militia Division. Elements of the Ryhmä 'Lagus' pressed on and reached the shores of Lake Onega on 23 September and cut the route to the south from Petrozavodsk.

The Finnish advance had compressed the defending Soviets into a small area in the vicinity of Petrozavodsk, with the 313^th Division keeping the sole remaining land route open. The advance of the 11^th Divisioona reached the town on 1 October but failed to close the escape route until on the following day. Meanwhile, the 1^st Divisioona, which had been clearing mottis near Pryazha, now reached the front and captured the town later on the same day. The fairly slow rate of the Finnish advance had made it possible for several Soviet units to escape from the encirclement, however. The fall of Petrozavodsk also broke the resistance in the south from from the Ryhmä 'Lagus' had been approaching the town. The 4^th Divisioona also finally broke through the Soviet defences at Besovets, leaving Petrozavodsk firmly in Finnish hands. The town was promptly renamed as Äänislinna by the Finns.

While most of the Finnish forces in the area had been concentrating on the capture of Petrozavodsk, elements of the 7^th Divisioona had advanced along the shore of Lake Onega to the mouth of the Svir river. The initial attempt to cross the river on 6 October failed as a result of fatigue and the men’s refusal, but a renewed attempt on the following day in bright daylight was successful. The rest of the division soon followed. This allowed merging of the bridgehead with that created earlier in the offensive. A Finnish attempt to gain good defensive ground came to an end at Oshta when their troops encountered the fresh 114^th Division: neither side could gain the advantage in the fighting that followed, and the Finns began to prepare for defence in the bridgehead to the south of the Svir river, which was expanded to a width of 62 miles (100 km) and 12.4 miles (20 km) in depth.

The capture of Medvezhyegorsk (Karhumäki in Finnish) was set as the goal for the continued offensive. Troops advancing from various directions toward the town were re-formed as the II Armeijakunta, which comprised the 4^th Divisioona, the Ryhmä 'Oinonen' and the Ryhmä 'Kuussari', and was further reinforced with Winell’s 8^th Divisioona on transfer from the Karelian isthmus. Opposing them was the Soviet operational group comprising the 37^th Division, 71^st Division and 313^th Division, all of which were now radically below strength. The Finns advanced along two routes: a larger group on the road from Petrozavodsk toward Medvezhyegorsk, and a smaller group on the road from Porosozero (Porajärvi in Finnish) toward Paatene at the south-western end of the Segozero lake.

After reaching Paatene, the advancing Finnish forces were able to establish lines of communication to Raappana’s 14^th Divisioona, which had earlier reached Rugozero. Medvezhyegorsk was captured on 5 December in a three-pronged attack, and on the following day the Finnish spearhead captured Poventsa (Povenets in Finnish). After Povenets had fallen, the Soviets destroyed the locks of the Stalin White Sea-Baltic Sea Canal on December 8, which caused the immediate flooding of Povenets. Damage from the flood was largely superficial, however. Mannerheim had earlier ordered that the advance of the Finnish forces come to a halt once it had reached a line running extending Povenets toward the Segozero lake, so the capture of Povenets ended the Finnish offensive.

During the five-month campaign, the Finns had suffered 75,000 casualties, including 26,355 dead, while the Soviets had suffered 230,000 casualties, of whom 50,000 were taken prisoner.

In the extreme north of Finland, the German objective in Finnish Lapland was the seizure of Murmansk and the severing of the Kirov railway linking this Arctic Ocean port and Leningrad by the capture of Salla and Kandalaksha. Murmansk was the only year-round ice-free port in the northern USSR, and forces based there posed a threat to the nickel-mining operation at Petsamo. A joint operation, known to the Germans as 'Silberfuchs' and the Finns as 'Hopeakettu', was begun on 29 June by the Armee 'Norwegen', which had two Finnish formations (Eversti Uno Fagernäs’s 3^rd Divisioona and Eversti Verner Viikla’s 6^th Divisioona) under command, against the Soviet 14^th Army and 54^th Division. By November, the operation had stalled 19 miles (30 km) from the Murmansk railway asa result of the German troops lack of acclimatisation, the strong Soviet resistance, the difficult terrain, the Arctic weather and US diplomatic pressure on Finland regarding the deliveries of Lend-Lease equipment to Murmansk. The offensive and its three sub-operations failed to achieve their objectives. Both sides dug in and the arctic theatre remained stable, excluding minor skirmishes, until the Soviet 'Petsamo-Kirkenes Offensive Operation' in October 1944.

The crucial deliveries of weapons and other Lend-Lease supplies to the Soviet forces by means of the convoys through the Arctic Ocean from the USA and the UK continued throughout World War II. The USA supplied almost US$11 billion in matériel: 400,000 Jeeps and trucks, 12,000 armoured vehicles (including 7,000 tanks, which could otherwise have equipped some 20 US armoured divisions), 11,400 aircraft, and 1.59 million tons of food. British shipments of Matilda, Valentine and Tetrarch tanks accounted for the equivalent of only 6% of total Soviet tank production, but more than 25% of medium and heavy tanks produced for the Soviet army.

The German forces advanced rapidly and deeply into the USSR early in the 'Barbarossa' campaign, and this led the Finnish government to believe that Germany would quickly defeat the USSR. Ryti envisaged a Greater Finland in which Finland and other Finnic people would live inside a 'natural defence borderline' by incorporating the Kola peninsula, East Karelia and perhaps even northern Ingria. In public, the proposed frontier was introduced with the slogan 'short border, long peace'. Some members of the Finnish parliament, such as members of the Social Democratic Party and the Swedish People’s Party, opposed the idea and argued that the maintenance of the 1939 frontier would be sufficient. Mannerheim often called the war an anti-Communist crusade, hoping to' defeat Bolshevism once and for all', and on 10 July Mannerheim drafted his order of the day, the 'Sword Scabbard Declaration', in which he pledged to liberate Karelia. During December 1941, in private letters he made known his doubts of the need to push beyond the previous borders. The Finnish government assured the USA that it was unaware of the order.

It has been argued that the majority of Finns thought that the scope of the new offensive was to regain only that which had been taken in the 'Winter War', and that the name 'Continuation War' was created at the start of the conflict by the Finnish government to justify the invasion to the population as a continuation of the defensive 'Winter War'. The government also wished to emphasise that Finland was not officially not an ally of Germany, but a 'co-belligerent' fighting against a common opponent and with purely Finnish aims. The authenticity of the government’s claim changed when Finnish forces crossed the frontier of 1939 and began to annex Soviet territory.

By the autumn of 1941, Finland’s military leadership had begun to doubt Germany’s capability to finish the war quickly. The Finnish forces had suffered relatively severe losses during their advance and, in overall terms, German victory became uncertain as German troops were halted to the west of Moscow. German troops in northern Finland faced terrain and climatic conditions for which they were unprepared, and thus failed to gain their objectives. As the front lines stabilised, Finland therefore attempted to start peace negotiations with the USSR. Mannerheim refused to assault Leningrad, which would link Finland inextricably to Germany: he regarded his objectives for the war to have been achieved, a decision that angered the Germans.

As a result of the war effort, the Finnish economy suffered from a lack of labour, as well as food shortages and increased prices. To combat this, the Finnish government demobilised part of the army to prevent industrial and agricultural production from collapsing. In October 1941, Finland informed Germany that it would need 159,000 tons of grain to manage until next year’s harvest. The German authorities would have rejected the request, but Hitler agreed and annual grain deliveries of 180,000 tons were equivalent to almost half of the Finnish domestic crop. In November, Finland joined the Anti-Comintern Pact.

Finland maintained good relations with a number of western nations. Foreign volunteers from Sweden and Estonia were among those who joined the Finnish ranks. The Jalkaväkirykmentti, called the soomepoisid (Finnish boys), comprised mostly Estonians, and the Swedes mustered a Swedish Volunteer Battalion. Stressing that Finland was fighting as a co-belligerent with Germany against the USSR only to protect itself, Finland claimed that it was still the same democratic country as it had been in the 'Winter War'. Finland maintained diplomatic relations with the Norwegian government-in-exile, and on more than one occasion criticised German occupation policy in Norway. Relations between Finland and the USA were more complex as the American public was sympathetic to the 'brave little democracy' and had anti-communist sentiments. At first, the USA was sympathetic to the Finnish cause, but the situation became problematic after the Finnish army crossed the 1939 border. Finnish and German troops were a threat to the railway and the northern supply line between the Western Allies and the USSR. On 25 October 1941, the USA demanded that Finland cease all hostilities against the USSR and withdraw behind the 1939 border. In public, Ryti rejected the demands, but in private wrote to Mannerheim on 5 November and asked him to halt the offensive. Mannerheim agreed and secretly instructed Siilasvuo to bring to an end his III Armeijakunta's assault on the railway.

On 12 July 1941, the UK signed an agreement on joint action with the USSR. Under German pressure, Finland closed the British legation in Helsinki and cut diplomatic relations with the UK on 1 August. The most sizeable British action on Finnish soil was the raid on Kirkenes and Petsamo, which was an attack by carrierborne aircraft on German and Finnish ships on 31 July. The attack accomplished little except the loss of one Norwegian ship and three British aircraft, but demonstrated British support for its Soviet ally. From September to October 1941, a total of 48 Hawker Hurricane single-engined fighters of the RAF’s No. 151 Wing, based at Murmansk, reinforced and provided pilot training to the Soviet air forces during 'Benedict' to protect Arctic convoys. On 28 November, the British government presented Finland with an ultimatum demanding that the Finns to cease military operations by 3 December. Unofficially, Finland informed the Allies that Finnish troops would halt their advance in the next few days, but this reply did not satisfy London, and the UK declared war on Finland on 6 December, the commonwealth nations of Canada, Australia, India and New Zealand soon following. In private, Winston Churchill, the British prime minister, had sent a letter to Mannerheim on 29 November in which he revealed that he was 'deeply grieved' that the British would have to declare war on Finland because of the British alliance with the Soviets. Mannerheim repatriated British volunteers under his command to the UK via Sweden.

In the first half of 1942, the Soviet forces undertook four attacks, all of which were repelled by Finnish and German troops.

Unconventional warfare was fought in both the Finnish and Soviet wildernesses. Finnish long-range reconnaissance patrols, organised both by the intelligence division’s 4^th Irrotettu Pataljoona (detached battalion) and by local units, patrolled behind Soviet lines. Soviet partisans, both resistance fighters and regular long-range patrol detachments, conducted a number of operations in Finland and in East Karelia from 1941 to 1944. In the summer of 1942, the USSR formed the 1^st Partisan Brigade: this was 'partisan' only in name as it was essentially 600 men and women committed on long-range patrols intended to disrupt Finnish operations. The 1^st Partisan Brigade was able to infiltrate beyond Finnish patrol lines, but was intercepted, and rendered ineffective, in August 1942 at the Segozero lake. Irregular partisans distributed propaganda newspapers, such as Finnish translations of the official communist party newspaper Pravda. Finnish sources state that although Soviet partisan activity in East Karelia disrupted Finnish military supply and communication assets, almost two-thirds of the attacks targeted civilians, killing 200 and injuring 50, including children and the elderly.

Between 1942 and 1943, military operations were limited, although the front did see some action. In January 1942, the Soviet Karelian Front attempted to retake Medvezhyegorsk (Karhumäki in Finnish). With the arrival of spring in April, Soviet forces went on the offensive on the Svir river front, in the Kestenga (Kiestinki in Finnish) region farther to the north in Lapland as well as in the far north at Petsamo, where the 14^th Division made amphibious landings supported by ships of the Northern Fleet. All the Soviet offensives started promisingly, but as a result either of the Soviets overextending their lines or stubborn defensive resistance, were repulsed. After Finnish and German counterattacks in Kestenga, the front lines were generally stalemated. In September 1942, the USSR attacked again at Medvezhyegorsk, but in five days of fighting the Soviets managed to push the Finnish lines back only some 545 yards (500 m) on a stretch of the front a mere 915 yards (1000 m) long. Later in that same month, a Soviet landing with two battalions in Petsamo was defeated by a German counterattack. In November 1941, Hitler decided to separate the German forces fighting in Lapland from those of the Armee 'Norwegen', and on 14 January 1942 the Armee 'Lappland' came into being under the command of Generaloberst Eduard Dietl. On 22 June 1942 the Armee 'Lappland' was redesignated as the 20^th Gebirgsarmee.

As noted above, in the early stages of the 'Continuation War', the Finnish army overran the former 1939 border, but ceased its advance some 18.5 to 20 miles (30 to 32 km) from the centre of Leningrad. Although many writers have stated that Finland participated in the siege of Leningrad, the full extent and nature of this participation is debated and there is as yet no consensus. According to one historian, during their meeting on 4 June 1942 Mannerheim personally refused Hitler’s request to assault Leningrad. Mannerheim explained to Hitler that 'Finland has every reason to wish to stay out of any further provocation of the USSR.'

The 150 speedboats, two minelayers and four steamships of the Finnish Laatokan laivastoyksikkö (Ladoga naval detachment), as well as numerous shore batteries, had been based on and round Lake Ladoga since August 1941. Ob 17 May 1942, Talvela the creation of a joint Finnish, German and Italian unit on the lake to disrupt Soviet supply convoys to Leningrad. The unit was named the Merivoimien Osasto 'K' (Naval Detachment 'K') and comprised four Italian MAS torpedo boats of the 12a Squadriglia MAS, four German KM-type minelayers and the Finnish torpedo boat Sisu. The detachment began operations in August 1942 and sank numerous smaller Soviet boats and barges, and assaulted Soviet bases and beach fronts until it was dissolved in the winter of 1942/43. Some 23 Siebel ferries and nine infantry transports of the German Einsatzstab Fähre 'Ost' were also deployed to Lake Ladoga and unsuccessfully assaulted the island of Sukho, which protected the main supply route to Leningrad, in October 1942.

Despite the siege of the city, the Soviet Baltic Fleet was still able to operate from Leningrad. The Finnish navy’s flagship, the coast-defence shipo Ilmarinen had been sunk in September 1941 in the gulf by mines during the failed diversionary 'Nordwind' (i) operation. Early in 1942, Soviet forces recaptured the island of Gogland, but lost it and the Bolshoy Tyuters island group to Finnish forces later in the spring of 1942. During the winter of 1941/42, the Soviet Baltic Fleet decided to use its large submarine fleet in offensive operations. Although initial submarine operations in the summer of 1942 were successful, the Kriegsmarine and Finnish navy soon intensified their anti-submarine efforts, making Soviet submarine operations later in 1942 altogether more costly. The Soviet submarine offensive convinced the Germans to lay anti-submarine nets as well as supporting minefields between the Porkkala peninsula of Finland and the Estonian Naissaar island, which proved to be an insurmountable obstacle for Soviet submarines. In the Arctic Ocean, Finnish radio intelligence intercepted Allied messages on supply convoys to Murmansk, and relayed the information to the German intelligence apparatus.

On 19 July 1941, the Finns created a military administration in occupied East Karelia with the goal of preparing the region for eventual incorporation into Finland. The Finns aimed to expel the Russian portion of the local population, which was deemed 'non-national', from the area once the war was over, and to replace the expelled part of the population with local Finnic peoples, such as Karelians, Finns, Ingrians and Vepsians. Most of the East Karelian population had already been evacuated before the Finnish forces arrived, but about 85,000 people (mostly the elderly, women and children and less than half of them Karelians) had been left behind. A significant number of civilians, almost 30% of the remaining Russians, were interned in concentration camps.

The winter of 1941/42 was especially harsh for the Finnish urban population as a result of poor harvests and a shortage of agricultural labourers. Conditions were much worse for Russians in Finnish concentration camps, however, in which more than 3,500 people (13.8% of those detained) died, mostly from starvation, while the corresponding figure for the free population of the occupied territories was 2.6%, and 1.4% for Finland. Conditions gradually improved, ethnic discrimination in wage levels and food rations was terminated, and new schools were established for the Russian-speaking population the following year, after Mannerheim called for the International Committee of the Red Cross from Geneva to inspect the camps. By the end of the occupation, mortality rates had dropped to the same levels as that in Finland.

Finland had a small Jewish population, totalling some 2,300 persons, of whom 300 were refugees. They had full civil rights and fought with other Finns in the ranks of the Finnish army. The field synagogue in East Karelia was one of the very few functioning synagogues on the Axis side during the war. The German command mentioned Finnish Jews at the Wannsee Conference in January 1942, expressing the desire to transport them to the Majdanek concentration camp in occupied Poland. Reichsführer-SS Heinrich Himmler also raised the topic of Finnish Jews during his visit in Finland in the summer of 1942, but Jukka Rangell, the Finnish prime minister, responded that Finland did not have a Jewish question. In November 1942, Toivo Horelli, the minister of the interior, and Arno Anthoni, the head of state police, secretly handed over eight Jewish refugees to the Gestapo, raising protests among Finnish Social Democrat Party ministers; only one of these deportees survived. After the incident, the Finnish government refused to transfer any more Jews to the Germans.

Finland had begun to seek an exit from the war after the German defeat at the 'Battle of Stalingrad' in February 1943. The Finnish prime minister, Edwin Linkomies, formed a new cabinet in March 1943 with peace as its highest priority. Similarly, the Finns were distressed by the Allied 'Husky' (i) invasion of Sicily in July and the defeat of the German 'Zitadelle' in the 'Battle of Kursk' in July and August. Negotiations were conducted intermittently in 1943 and 1944 between Finland, the Western Allies and the USSR, but no agreement was reached. Iosef Stalin decided to force Finland to surrender with a bombing campaign against Helsinki. Starting in February 1944, this campaign included three major air attacks totalling more than 6,000 sorties. The Finnish anti-aircraft defences repelled the raids, and only 5% of the dropped bombs hit their planned targets. In Helsinki, decoy searchlights and fires were placed outside the city to deceive Soviet bombers into dropping their payloads on unpopulated areas. Major air attacks also hit Oulu and Kotka, but pre-emptive radio intelligence and effective defence kept the number of casualties low.

The Soviet 'Leningrad-Novgorod Strategic Offensive Operation' finally lifted the siege of Leningrad on 26/27 January 1944 and drove the German forces of Heeresgruppe 'Nord' into Ida-Viru county on the Estonian border. Stiff German and Estonian defence in Narva from February to August prevented the use of occupied Estonia as a base for Soviet amphibious and air assaults against Helsinki and other Finnish coastal cities in support of a land offensive. Mannerheim had reminded the German command on numerous occasions that if the German troops withdrew from Estonia, Finland would be forced to make peace, even on extremely unfavourable terms, but nonetheless Finland abandoned peace negotiations in April 1944 because of the unfavourable terms the USSR demanded.

On 10 June 1944, the Soviet Leningrad Front launched the 'Vyborg Offensive Operation' against the Finnish positions on the Karelian isthmus and in the area of Lake Ladoga, timed to coincide with the launch of the Western Allies 'Overlord' in Normandy as agreed during the Tehran Conference. Along the 13.5-mile (21.7-km) breakthrough front, the Soviets had 3,000 guns and mortars. In some places, the concentration of artillery pieces exceeded 200 guns per kilometre of front or one for every 5.5 yards (5 m). The Soviet artillery fired more than 80,000 rounds along the front on the Karelian isthmus. On the second day of the offensive, the artillery barrages and superior number of Soviet forces crushed the main Finnish defence line. The Soviet forces penetrated the second line of defence, the 'Vammelsuu-Taipale Linje' (VT-Line), by the sixth day and recaptured Viipuri against insignificant resistance on 20 June. The Soviet breakthrough on the Karelian isthmus forced the Finns to reinforce the area, thus giving the concurrent 'Petrozavodsk Offensive Operation' in East Karelia less resistance and allowing it to recapture Petrozavodsk by 28 June 1944.

On 25 June, the Soviet forces reached the third line of defence, the 'Viipuri-Kuparsaari-Taipale Linje' (VKT-Line), and the decisive 'Battle of Tali-Ihantala' began. By then, the Finnish army had retreated about 60 miles (100 km) to approximately the same line of defence they had held at the end of the 'Winter War'. Finland was notably lacking in modern anti-tank weaponry that could stop Soviet heavy armour, such as the KV-1 and IS-2 heavy tanks. Thus, the German foreign minister, Joachim Ribbentrop, offered German hand-held Panzerfaust and Panzerschreck anti-tank weapons in exchange for a guarantee that Finland would not seek a separate peace with the Soviets. On 26 June, President Ryti gave the guarantee as a personal undertaking that he, Mannerheim and prime minister Edwin Linkomies intended to last legally only for the remainder of Ryti’s presidency. In addition to delivering thousands of anti-tank weapons, Hitler sent Generalmajor Hero Breusing’a 122^nd Division and Hauptmann Fritz Scherer’s half-strength 303^rd Sturmgeschützbrigade equipped with Sturmgeschütz III assault guns as well as the Luftwaffe’s Gefechtsverband 'Kuhlmey' to provide temporary support in the most vulnerable sectors. With the new supplies and assistance from Germany, the Finnish army halted the numerically and materially superior Soviet advance at Tali-Ihantala on 9 July 1944 and stabilised the front.

More battles were fought toward the end of the war, the last of which was the 'Battle of Ilomantsi', fought between 26 July and 13 August 1944 and resulting in a Finnish victory with the destruction of two Soviet divisions. Resisting the Soviet offensive had exhausted Finnish resources, however, and despite German support under the Ryti-Ribbentrop agreement, Finland asserted that it was unable to blunt another major offensive. Soviet strategic victories against the German Heeresgruppe 'Nord' and Heeresgruppe 'Mitte' during 'Bagration' rendered the situation still more dire for Finland. With no imminent further Soviet offensives, Finland sought to leave the war. On 1 August, Ryti resigned and on 4 August Mannerheim took office as Finland’s new president. Mannerheim annulled the agreement between Ryti and Ribbentrop on 17 August to allow Finland once more to sue for peace with the Soviets, and peace terms from Moscow arrived on 29 August.

Finland was required to return to the borders agreed to in the 1940 Moscow Peace Treaty, demobilise its armed forces, fulfil war reparation demands and cede the Petsamo area. The Finns were also required immediately to end diplomatic relations with Germany and to expel the German forces from Finnish territory by 15 September 1944; any troops remaining were to be disarmed, arrested and turned over to the Allies. The Finnish parliament accepted those terms in a secret meeting on 2 September and requested for official negotiations for an armistice to begin. The Finnish army implemented a ceasefire at 08.00 on 4 September, and the Soviet forces followed suit a day later. On 14 September, a delegation led by Antti Hackzell, the Finnish prime minister, and Carl Enckell, the foreign minister, began negotiating with the USSR and UK the final terms of the Moscow armistice, which eventually included additional stipulations from the Soviets. They were presented by Molotov on 18 September and accepted by the Finnish parliament one day later.

The motivations behind the Soviet peace agreement with Finland are debated. Several Western historians stated that the original Soviet designs for Finland were no different from those for the Baltic countries. A US political scientist asserted that for Moscow, the control of Finland was necessary. Molotov has been quoted as telling his Lithuanian counterpart in 1940, when the Soviets effectively annexed Lithuania, that minor states such as Finland 'will be included within the honourable family of Soviet peoples'. It has also been argued that Soviet concerns about severe losses pushed Stalin into accepting a limited outcome in the war rather than pursuing annexation, although some Soviet documents called for military occupation of Finland. Stalin had described territorial concessions, reparations and military bases as his objective with Finland in talks with British representatives in December 1941, and with US representatives in March 1943, as well as the Tehran Conference. Thus, it is claimed, 'Stalin’s desire to crush Hitler quickly and decisively without distraction from the Finnish sideshow' concluded the war. Soviet officers captured during the 'Battle of Tali-Ihantala' revealed that the Soviet intention was to reach Helsinki, and that their forces were to be reinforced for this task. This was confirmed by intercepted Soviet radio messages.

Russian historians have disputed the view that the USSR sought to deprive Finland of its independence, arguing that there is no documentary evidence for such claims and that the Soviet government was always open for negotiations. Sources such as the public information chief of Finnish headquarters, Major Kalle Lehmus, have been cited to show that Finnish leadership had learned of the limited Soviet plans for Finland by a time no later than July 1944 after intelligence had revealed that some Soviet divisions were to be transferred to reserve in Leningrad. However, evidence of the Soviet leadership’s intentions for the occupation of Finland was later uncovered: in 2018, it was revealed that during the closing stages of the 'Continuation War' the Soviets designed and printed new banknotes for Finland to be placed into circulation after the planned occupation of the country.

According to Finnish historians, the Finnish casualties totalled 63,204 dead or missing and around 158,000 wounded. Officially, the Soviets took prisoner 2,377 Finns, but Finnish researchers have estimated the number to be around 3,500. A total of 939 Finnish civilians died in air raids and 190 civilians were killed by Soviet partisans. Germany suffered some 84,000 casualties on the Finnish front: 16,400 killed, 60,400 wounded and 6,800 missing.

In addition to the original peace terms of restoring the 1940 border, Finland was required to pay war reparations to the USSR, conduct domestic war-responsibility trials, cede Petsamo and lease the Porkkala peninsula to the Soviets, and also to ban Fascist elements and allow left-wing groups, such as the Communist Party of Finland. A Soviet-led Allied Control Commission was installed to enforce and monitor the peace agreement. The requirement to disarm or expel any German troops left on Finnish soil by 15 September 1944 eventually escalated into the 'Lapland War' ('Lapinsota') between Finland and Germany, and to the evacuation of the 200,000-man 20^th Gebirgsarmee into northern Norway.

The Soviet demand for US$600 million in war indemnities was reduced to US$300 million, most likely as a result of US and British pressure. After the ceasefire, the Soviets insisted for the payments to be based on 1938 prices, which doubled the de facto amount. The interim Moscow Armistice was later finalised without changes in the Paris Peace Treaties of 1947. Thus Finland survived the war without losing its independence, unlike many of Germany’s other allies. Likewise, Helsinki, along with Moscow, was the only capital of a European combatant nation that was not occupied.

Many civilians who had been displaced after the 'Winter War' had moved back into Karelia during the 'Continuation War' and so had to be evacuated from Karelia again. Of the 260,000 civilians who had returned Karelia, only 19 chose to remain and become Soviet citizens. Most of the Ingrian Finns, together with Votes and Izhorians living in German-occupied Ingria, had been evacuated to Finland in 1943/1944. After the armistice, Finland was forced to return the evacuees. The Soviet authorities did not allow the 55,733 returnees to resettle in Ingria and deported the Ingrian Finns to central regions of the USSR.

In the USSR, the 'Continuation War' was considered a Soviet victory. According to Finnish historians, Soviet casualties in the 'Continuation War' were not accurately recorded and various approximations have been calculated. One Russian historian has estimated that about 250,000 Soviet soldiers were killed or missing in action while 575,000 became medical casualties (385,000 wounded and 190,000 sick). Other historians that at least 305,000 Soviet soldiers were confirmed dead or missing, and that the number of wounded certainly exceeded 500,000. The total of Soviet prisoners of war in Finland was estimated by Finnish historians to be around 64,000, 56,000 of whom were captured in 1941. Some 2,600 to 2,800 Soviet prisoners of war were rendered to Germany in exchange for approximately 2,200 Finnic prisoners of war. Of the Soviet prisoners, at least 18,318 were documented to have died in Finnish prisoner of war camps.

The extent of Finland’s participation in the siege of Leningrad, and whether Soviet civilian casualties during the siege should be attributed to the 'Continuation War', is debated and lacks a consensus: estimates of civilian deaths during the siege range from 632,253 to 1,042,000.

It has been claimed that the Soviet forces lost 697 tanks destroyed, 842 pieces of field artillery captured and some 1,600 aircraft destroyed by Finnish fighters, 1,030 by anti-aircraft fire and 75 by the navy.