How a Finnish Polka Song Defeated The Mighty Red Army

Three months after Hitler invaded Poland triggering a series of nasty and costly wars across the world, the Soviet Union took the opportunity to invade Finland to settle some longstanding political issues, mostly to take land from Finland to use it as a buffer between the newly christened city of Leningrad and the rising power of Nazi Germany. The Finnish fought hard in freezing temperatures and repelled Soviet attacks for two months, inflicting substantial losses on the invaders initially. But the Red Army came back hard and overcame Finnish defenses during the later stages of the war. Hostilities finally ceased with the signing of the Moscow Peace Treaty, but it was Finland who got the short end of the stick. They were forced to ceded substantial territory to the Soviet Union amounting to nearly one-tenth of their entire land, which translated to a loss of 30 percent of its economic assets. Understandably, the conditions of the peace treaty left Finland bitter. The world was sympathetic to the Finnish cause and the Soviet aggression was deemed unjustified. Fifteen months later, when Nazi Germany prepared for an invasion of the Soviet Union, Finland joined in hoping that a combined attack would bring the mighty Soviet Union down to its knees and Finland would regain its lost territories. This second conflict was called the Continuation War.

Finnish soldiers celebrate after recapturing Viborg in August 1941.

Finland with the help of Hitler’s army managed to drive back the Soviet army and by the summer of 1941, just three months into the war, Finland had regained all of its territory that it had lost to the Soviet Union during the Winter War and more. As the Red Army retreated from the city of Vyborg on the Karelian Isthmus, about 130 km to the northwest of St. Petersburg, they hid radio-controlled mines throughout the region.

At first the Finns wondered at the strange mine explosions that seemed to go off at random times. They suspected they might be time-triggered. Then on August 28, 1941, the Finnish army found around 600 kg of explosive charge installed under the Moonlight Bridge. The charge was rigged to a strange device, apparently the trigger. The troops quickly delivered the device to the Communications Department where Captain of Engineering Jouko Pohjanpalo, an expert in radio communications, dismantled the device and discovered that the trigger was radio controlled. Inside the radio receiver were three sound irons that oscillated at specific frequencies. When the three of them vibrated together, in response to a three-note chord that was played on the frequency the radio was tuned to, the mine exploded.

Map of the areas ceded by Finland to the Soviet Union after the Winter War 1940. Image: Wikimedia Commons

In order to prevent the Soviets from triggering the mines, they needed a jamming signal at that specific frequency. Usually, a jamming frequency is a high-powered white noise, but in this case the triggering frequency was 715 kHz, which was within the AM band used by radio. Any signal broadcast on that frequency could be heard on a radio receiver tuned to that particular frequency. So why not transmit music at the jamming frequency instead of random noise? A fast-paced polka song called Säkkijärvi polkka was chosen and was played on loop 24 hours a day by the Finnish public broadcasting company Yleisradio. When the Russians realized what the Finns were doing, they changed the triggering frequency. In the meantime, an examination of the dismantled triggers had revealed that radio mines could be operated on three different radio frequencies. So the Finns began playing Säkkijärvi polkka on all the three frequencies. This continued non stop for three months, until the batteries in the mines had depleted. The strategy was so effective that out of one thousand or so mines in the city, only 12 went off.

After the war, Säkkijärvi polkka became one of the country's most prized national mementos, a sort of “honorary national anthem”, as it signified their defiance against the Soviets' occupation. Over the years the polka has become popularized by a number of musical groups such as Viljo "Vili" Vesterinen, the Oulu Hotshots, and Netta Skog.

Listen to this famous Finnish folk song below.