The 'Uuksu-linja' was a Finnish position on the Karelian front, during the 'Jatkosota', for Kenraaliluutnantti Karl Lennart Oesch’s (from 14 June Kenraaliluutnantti Paavo Tqlvela’s) Karjalan Armeija (Karelian Army) against the Soviet forces of General Kirill A. Meretskov’s Karelia Front and extending between Pitkärantal, on the north-eastern corner of Lake Ladoga, in a nearly straight line to the north (June/July 1944).

Constructed from a time late in the winter of 1943, the 'U-linja' shielded Nietjärvi, Lemetti and Loimola as the key points in Finland’s Karelian defences behind the 'PSS-linja' centred on Pisi, Saarimäki and Sammatus, which was the strongest defence line in the area to the north and north-east of Lake Ladoga in the Olonets Karelia region between Lakes Ladoga and Onega. Up to this time, the Finnish front had extended mainly along the line of the canalised Svir river, which flows from Lake Onega to Lake Ladoga. Behind this was a secondary defence line in front of the 'PSS-linja', and the Finns hoped that these lines would check if not halt any Soviet offensive to the north-west between Lake Onega, which could be outflanked to the north between Lakes Onega and Segozero by General Leytenant Filipp D. Gorelenko’s three-division 32^nd Army.

Although the Soviet primary offensive by Meretskov’s Karelia Front had started on 10/11 June as General Leytenant Aleksandr I. Cherepanov’s 23^rd Army and General Leytenant Dmitri N. Gusev’s 21^st Army moved to the north-west in the direction of the 'VT-linja' between Lake Ladoga and the Gulf of Finland, the more northern part of the Soviet offensive began only on 20 June, when Gorelenko’s 32^nd Army went over to the offensive between Povomets on Lake Onega and Maselskaya on Lake Segozero against Kenraalimajuri Einar Mäkinen’s Finnish II Corps.

However, the main attack in these sectors was launched on the following day by General Leytenant Aleksei N. Krutikov’s 14-division 7^th Army between Lake Onega and Lake Ladoga against Kenraalimajuri Armas-Eino Martola’s Finnish VI Armeijajunta (corps) and Talvela’s Aunuksen Ryhmä (Olonets Group). For three weeks the Finns were able to slow but not to halt the advance of the 7^th Army, which lost large numbers of men as well as more than 200 armoured fighting vehicles and something approaching 200 aircraft.

What was altogether too clear was that the defences in front of the 'U-linja' were inadequate in the face of the Soviets' overwhelming superiority in men, armour, artillery and air power.

The 7^th Army was now making local attacks near the 'U-linja' in order to locate the weakest spots in the defences and thus the best possible point at which to attempt a breakthrough. Attacks were made in the direction of Loimola, Katitsanlampi and Lemetti, among other places, but with these efforts the Soviets were not able to break through to the 'U-linja'. By now, though, the 7^th Army had come to the decision that the key to the 'U-linja' was Nietjärvi, whose capture would open the way to Kittilä, whose seizure would in turn provide axes of advance toward the area of Sortavala, Värtsilä and Matkaselkä. The renewed Soviet offensive was scheduled to start on 15 July, and on this day the Finnish defence was centred on Kenraalimajuri Kustaa Tapola’s 5^th Divisioona (division), which was disposed with Everstiluutnantti Ilmari Rytkönen’s 44^th Jalkaväkirykmentti (infantry regiment) between Lake Ladoga and Nietjärvi, and Eversti Heikki Saure’s 2^nd Jalkaväkirykmentti on the north-eastern side of Nietjärvi. On the morning of 15 July Soviet artillery and mortars opened an intense preliminary bombardment of the Finnish positions, followed by a one-hour barrage of still greater intensity. Then the Soviet infantry and armour surged forward, and a crucial battle started on the western side of Nietjärvi, where a Soviet regiment attacked with very powerful armoured support.

By 12.00 the Finnish defence had managed to stop the Soviet attacks everywhere except on the western side of Nietjärvi where, in a poorly prepared outpost as well as on the Maximov line the 1/44^th Regiment and 3/44^th Regiment were being overwhelmed. The skill and courage of the two Finnish battalions were being put to the severest possible test, and during the afternoon the Soviets were able to make another and yet more dangerous breakthrough on the north-western shore of Lake Nietjärvi at Yrjölä. The Soviets were now approaching the point at which they could gain access the road leading connecting Yrjölä and Kittilä. With all their local reserves already committed, the Finns needed reinforcements, and Martola allocated Majuri Erik Väänänen’s 4^th Pataljoona (battalion) of Eversti Aloys Kuistio’s 15^th Prikaati (brigade) to the 5^th Divisioona.

By the evening of 15 July the Finns had succeeded in halting the Soviet breakthrough attempt, and had even managed to drive the Soviets back in all the most threatening sectors except one very highly concerning spearhead some 435 yards (400 m) wide. Throughout the evening the Soviet offensive continued relentlessly with the support of some 200 aircraft. On the Finnish side, Everstiluutnantti Birger Gabrielsson’s 4^th Lentorykmentti (air regiment) attacked the Soviet forces on the south-eastern edge of Lake Nietjärvi.

During the same evening Tapola ordered Rytkönen to ensure that his 44^th Rykmentti destroyed the Soviet detachment which had broken through to a Finnish outpost behind the lake. Launched in the morning, the counterattack was led by Majuri E. Pokkinen and Majuri Erik Väänänen, and encountered very determined armour-backed Soviet resistance. Thus there was continuous heavy fighting throughout the day. The Soviets maintained their hold on part of the Nietjärvi village, and a long trench (or line of connected trenches) on a low hill in that area. Because a direct infantry attack toward this area would have resulted in very heavy casualties, the Finns opted to approach the trench system from each end as their artillery and mortars prevented any more Soviet troops entering the area. At 22.30, on 16 July, the Finnish artillery and mortars fired about 1,000 rounds into this Soviet breakthrough area, and immediately after this the Finnish infantry began to roll up the trench system from each end. During the early morning of 17 July the Finnish units were slowly eating into the length of the trench system still held by the Soviets, and the Finnish net was closing all round the Soviet position. The 1^st Pataljoona of the 15^th Prikaati led the advance from the south-west, and the same brigade’s 4^th Pataljoona advanced from the north-east. Soviet armour attempted to support the infantry remnants in the trench system, while the Finnish artillery and mortars nicely co-ordinated fire prevented the incursion of more Soviet troops. In the early morning there were clear signs that the surviving Soviets were on the verge of surrendering: only a few men had managed to escape, the bottoms of the trenches were full of dead, and the Finns were still pushing forward. Finally the last survivors yielded, and the 7^th Army had not been able to penetrate the 5^th Divisioona's defences in the 'U-linja'.

The heaviest Soviet losses were sustained by the 114^th Division, whose 762^nd Regiment had been totally destroyed. Most of the 114^th Division’s two other regiments had also been destroyed, and the 272^nd Division had suffered heavy losses. The 40 to 50 Soviet tanks which had attacked in the direction of Nietjärvi were also lost.

In overall terms, therefore, the breakthrough attempt had cost the Soviets more than 6,000 casualties, of which more than 2,000 were dead. In a little more than three weeks between 21 June and 17 July, therefore, the 7^th Army had sustained more than 45,000 casualties. The Finns, too, also lost heavily, with 11,250 men dead, missing or wounded: the 5^th Divisioona had lost 4,450 men, Kenraalimajuri Einar Vihma’s 8^th Divisioona 1,550 men, Kenraalimajuri Selim Isakson’s 7^th Divisioona 3,550 men, and the 15^th Prikaati 1,600 men. In the Nietjärvi area the Finns lost 700 men.

The air defence element of the Aunuksen Ryhmä) shot down 119 Soviet aircraft between 21 and 30 June, and 95 more between 1 and 18 July. The Finnish defence had thus prevented the Soviet forces from advancing from the north-eastern side of Lake Ladoga and then wheeling left to take the three Finnish corps of the Karelian isthmus defences in the rear or in flank.