 The construction of the U defense line had been launched seven months earlier on the level of Nietjärvi – Lemetti – Loimola, as the fortified line behind the PSS-line (Pisi – Saarimäki – Sammatus), which was the most heavily fortified defense line in the Olonets Karelia (north and northeast of Lake Ladoga).The frontline—up till July 1944—had been following closely the banks of the River Svir, which flows from Lake Onega to Lake Ladoga.Before battles even begun Finns abandoned the bridgehead which they had occupied on the southern shore of Svir when troop transfers to the Karelian Isthmus made it impractical to hold.