The Säkkijärven Polkka: When The Finns Used Their Jam To Jam Soviet Radio Controlled Mines

It’s safe to say that the Finnish were brilliant and unconventional when it came to war tactics, and they proved that during Winter War. They had this Motti tactic to immobilize and destroy Soviets army columns by blocking the road with a bundle of logs. There was also this one bizarre time when they annihilated an entire Soviet battalion who stopped their attack to eat Finnish sausage stew they found while overrunning their mess tents. The tactics continued during the Continuation War. In this particular instance, they utilized a folk song called Säkkijärven polka to stop the Soviet mines from detonating.

Vyborg Mines

When the Winter War between the Soviet Union and Finland ended in 1940, they signed the Moscow Peace Treaty, and a ceasefire immediately followed. However, the peace did not last long. The hostilities resumed just 15 months after the Winter War ended when Finland decided to ally with the Nazis to invade. They wanted to regain the territories they lost in the Winter War. This second conflict was called Continuation War.

The Finns succeeded in taking back the city of Vyborg from the USSR, driving Red Army units into a retreat. Of course, the Soviets wouldn’t just back down without a fight, so they rigged the city with mines and explosives while retreating. There were so many of these mines that many Finnish soldiers died from their explosions, and civilians were not allowed to return to their homes even after the city was reclaimed.

What confused the Finns was that the mines kept detonating, even when no one was setting them off. The initial theory was that these mines were set on timers, it was not until August 1941, when they discovered 1300 pounds of explosives along with its triggering device. They found out that these mines were not rigged with timers but triggered through radio signals.

Jouko Pohjanpalo

They immediately brought the devices to the Finnish Communications Department, where Juoko Pohjanpalo, the Captain of Engineering and expert in radio communications discovered that these ingenious triggering devices included a radio receiver with three tuning forks that vibrated at specific frequencies. A specific three-note radio transmission would cause these forks to vibrate and set off the mines. And so the Finns found out that the explosives scattered around their reclaimed city were all radio-operated.

The next thing they had to do before disposing of the mines was to stop the Soviets from detonating them; they needed to send a signal that would prevent the three-note sequence from triggering the mines, but this jamming signal itself shouldn’t set the mine off.

Operation Säkkijärven polkka

The “Säkkijärven polkkais” is a well-known folk song from Finland and was popularized by Finnish accordionist and composer Viljo “Vili” Vesterinen(Surely you have at least one of his albums, right?)

In September 1941, a loudspeaker-equipped bus was driven through Vyborg blasting the Säkkijärven polka nonstop at 715 kHz to block the USSR’s detonation signal. Soon enough, the Soviets figured out what was going on and changed and tripled the number of frequencies their detonation transmission was carried on. Responding in kind, the Säkkijärven polka was played on every frequency that the Soviets could possibly be using. The song continued broadcasting without a pause for three consecutive days, playing it about 1,500 times, while Finnish engineers searched for and disarmed the mines. In an interview, Pohjanpalo said, “All kinds of rumors circulated about somebody crazy enough to have emitted it on every radio station.” But the plan worked, as only 12 of the 1000 mines exploded.

If you’re curious to hear the song that saved Vyborg City, here it is:

What did you think of Finns’ plan? Was it brilliant or something else?