Following the operations in the Sortavala region, the corps's organization underwent significant change as its divisions were transferred to other units. In turn, the 10th and 15th divisions were transferred from II Corps to I Corps. The corps headquarters was thus moved to the Karelian Isthmus, where it participated in the Finnish invasion of the Karelian Isthmus. The 10th Division was engaged in the area between the river Vuoksi and Lake Krasnoye, while the 15th Division was in the area of river Vuoksi and Lake Sukhodolskoye on the northern side of the river. On 27 August, the corps continued the attack towards Leningrad, eventually reaching an area between Lembolovo and Lake Ladoga, where it halted and prepared a defensive posture beginning from 9 September.
