Soviet 1944 offensive had started on June 10, 1944 and in matter of days broke through of the fortified Finnish defense lines in southern Karelian Isthmus. On June 20 the advancing Soviet forces were already literally on the gates of Viipuri.
Soviet 1944 counteroffensive began on June 10, 1944, and swiftly breached the fortified Finnish defensive positions in southern Karelian Isthmus. By June 20, Soviet forces had reached the outskirts of Viipuri.