Finnish victory parade in front of the Round Tower of Viipuri (Vyborg) after the recapture of the town from the Red Army, 31 August 1941. Shortly after this, all the Finnish radio stations began playing a hectic 'Säkkijärven'- polka non-stop for nearly two weeks. The people at the rear learned afterwards that the withdrawing Soviet troops had placed explosive charges all over the town, which could be detonated by radio signal. The fast-paced music playing on all frequencies was enough to disrupt these signals as the Finnish pioneers raced to defuse each bomb! Previously, Viipuri (including all of the Karelian Isthmus) had been ceded to the Soviet Union on March 13, 1940, in the Moscow Peace Treaty, which marked the end of the Winter War. Later, in the summer of 1944, the Soviet Union reconquered the southern part of the isthmus from the Finns in the Vyborg-Petrozavodsk Offensive.
Book "Finland at War: The Continuation and Lapland Wars 1941-45 by Vesa Nenye