The 163rd German Infantry Division, on the Army of Karelia’s left flank, ran into difficulties north of the rail line between Loymola and Suvilakhti. This area is interspersed with numerous lakes that channel any advances and therefore favored the Soviet defenders. The German soldiers, not used to fighting in a forest wilderness, had difficulties from the start. An attempt on July 16 to capture Suvilakhti by forces advancing from Loymola failed.
The VI Corps sent a force from the Tulm Lake area to help the Germans. This force cut the railroad between Suvilakhti and Petrozavodsk east of Suvilakhti on July 26. However, the German division was still unable to resume its advance at the end of July and Mannerheim sent Group Oinonen with its two brigades to its assistance—the cavalry brigade and the 2nd Light Infantry Brigade under Colonel V. Sundman. These forces had assembled in the Ilomantsi area in preparation for their missions in the Ladoga Karelia offensive. During the first part of that offensive the cavalry brigade and light infantry brigade slowly made its way in the direction of the upper Aitto River east of Suo Lake against stiff Soviet resistance.
The attack in the Lake Suo area by German and Finnish forces from two directions (south and west) needed systematic preparation and several weeks passed before it was executed. The Finnish forces from Group Oinonen were merged with the 163rd Division and named Battle Group Engelbrechtunder, under the command of Lieutenant General Engelbrecht. Even this combined force found the going difficult. It was not until August 4 that the 2nd Light Infantry Brigade and the German 307th Infantry Regiment began their attack on the village of Aglajarvi east of Tolvayarvi, which was captured the following day. The Finnish Cavalry Brigade cut the road between Alajarvi and Tolvayarvi and made contact with the 2nd Light Infantry Brigade on August 6. The Soviets retired behind the Aitto River to avoid encirclement.
The 11th Finnish Division was located to the south of Battle Group Engelbrecht and it moved northward and reached the Petrozavodsk railroad on August 19. This unit continued northward and captured Suvilakhti on August 21. The 2nd Light Infantry Brigade, the Cavalry Brigade, and the German 307th Infantry Regiment crossed the Aitto River on 19 August. The Cavalry Brigade tried to encircle the enemy forces east of the river but the Soviets recognized the danger and withdrew before the 11th Division cut their last escape route at Tsalkki on August 23. While VII Corps established a front in the narrows between Lakes Syam and Shot, the 163rd Division was withdrawn from the front and stationed at the rear of the Army of Karelia as Mannerheim’s strategic reserve.
On the right wing of the Army of Karelia, the VII Corps also began its offensive on July 10, but its advance was not as spectacular as that of VI Corps. Its offensive was launched from the area between Lakes Pyha and Yanis. VII Corps pressed the stubborn enemy slowly southward and by the end of the month had reached the town of Ruskeala. A division detached from VI Corps occupied defensive positions along the Yanis River between the lake by that name and Lake Ladoga. The Soviets were facing and fighting in two directions—against the forces at Ruskeala in the north and the division along the Yanis River in the east. Under constant pressure and in order to avoid encirclement, the Soviets withdrew slowly in the direction of Sortavala.
The Army of Karelia had gone into defensive positions on orders from Mannerheim on July 19 and after minor local advances ended up along a line with Group Oinonen in the north, VII Corps in the center, and VI Corps in the south. General Talvela, commander of VI Corps, was not happy with the halt as indicated by a conversation he had with General Engelbrecht, commander of the 163rd German Division, on September 2. Ziemke quotes the operational log of the 163rd Division pertaining to this conversation:
Talvela said he regretted that his sector had been left completely inactive for the past several weeks even though he had repeatedly tried to get permission to resume the attack. He regretted the inactivity the more since the impact of his first advance had thrown the Russians into a panic which in his opinion would have made it “positively easy” at that time to push to the Svir and, possibly, create a bridgehead across it. The entire advance to the Tuloksa River line, he said had cost the VI Corps 3,500 casualties; the period of inaction since had cost as many.17
On the Army of Karelia’s right flank, II Corps occupied the border between Vuoksi River and Pyha Lake. It did not begin its offensive until July 31. The corps’ immediate objective was the railroad junction at the town of Khitola. Its capture would completely isolate the Soviet forces in the Sortavala area. The offensive made excellent progress and Mannerheim, who had earlier detached the 10th Division from the IV Corps as his reserve, committed that division on August 6 to exploit the success. In a rapid advance the 10th Division reached the shore of Lake Ladoga at the town of Lakhdenpokhya (Lahdenpohja). The main force of II Corps captured Khitola on August 11, the same day that a more southern column from the corps reached the shore of Lake Ladoga between Kegsgolm (Käkisalmi) and Khitola.
The Soviet forces, caught in a pocket between the forces of VII Corps in the east and north and those of II Corps in the west and north, were split into two groups by the advancing Finns. A group of about two divisions found itself isolated by II Corps forces in the vicinity of the town of Kyrikiyoki. The Soviets put up a fierce resistance despite their desperate situation. Many managed to withdraw to Kilpola (Kilpolansaari), a large island connected to the mainland by a causeway. The Soviets were evacuated by sea in mid-August but suffered heavy losses in men and ships. The fighting at Kilpola was concluded on August 24. The area of the Karelian Isthmus between Lake Ladoga and Vuoksi River was now in Finnish hands.
The Russian division fighting in the area west of Sortavala was pressed against the shore of Lake Ladoga between Lakhdenpokhya and Sortavala. After fierce resistance it was surrounded at Rautalahti. Resistance ceased on August 20. Some of the Soviet troops managed to escape by ship to Valaam Island.
Mannerheim made some further organizational changes before moving against Sortavala. He moved the VII Corps Headquarters to the area between the VI Corps and the 163rd German Infantry Division. The units that had been under VII Corps control—7th and 19th Divisions—were placed under the control of the newly created I Corps, as was the 2nd Division from II Corps. It was I Corps that took over the attack on Sortavala. The Soviet forces defending the city could not hold out against simultaneous Finnish attacks from three directions and Sortavala was captured on August 16. Most of the Soviet troops escaped by sea to Valaam Island and from there they were transported to the Leningrad area. Finnish and German aircraft could not prevent the Soviet evacuation.