Launched by a British plane in April 1945, in a raid targeting a German cruiser, the huge device, over five tons, called Tallboy and capable of causing a small earthquake, was located last year, during the dredging of the access road to the port. Szczecin, in the northwestern tip of Poland.

“It’s a world premiere. No one has ever neutralized such a well-preserved Tallboy, who lies on the seabed, “a spokesman for the Polish Coast Defense Fleet stationed at Swinoujscie, Grzegorz Lewandowski, told AFP.

About 750 residents of the 2.5-kilometer security zone were urged to leave their homes during the day, during this high-risk operation, which could last a total of five days, according to the Navy.

During the operation, traffic and maritime traffic will be “paralyzed” in this port and border town of 40,000 inhabitants, spread over 44 inhabited or wild islands, announces, near the town hall, Jaroslaw Jaz, from the Department for Crisis Management .

Deflagration destruction

“Preparations are taking place in the first two or three days. Our genius divers must dig around the bomb sunk in the channel bed, 12 meters deep. Only the tip is out, “Lewandowski told AFP.

“It’s very delicate. The device must not be moved, no shock is allowed. The slightest vibration risks triggering the explosion “, he states.

Due to the care of the life of engineers and residents, residents and infrastructure in the area, especially a bridge that is only 500 meters away, engineers have excluded the traditional method of detonation, the most common, but also the most violent.

“The water safety zone is set at 16 kilometers” for this bomb over six meters long, filled with 2.4 tons of explosive, whose power is equivalent to 3.5 tons of trinitrotoluene (TNT), says the spokesman .

The engineers chose to use the process of “deflagration which consists, in large part, in a combustion of the explosive charge at a temperature higher than the detonation threshold”, explains Lewandowski.

Once installed on the pump body, a remote-controlled, trigger-triggered device will pierce the pump housing and trigger combustion.

Swinoujscie genius divers regularly apply this five-year method to lower-powered bombs found around the canal, the site of massive World War II bombings.

Lancasters against a Lutzow

Swinoujscie – Swinemünde in German – was during the two world wars one of the most important bases of the German Navy in the Baltic Sea, recalls historian Piotr Laskowski, author of a detailed book on the British Royal Air Force (RAF) raid against the cruiser Lützow , then anchored on the canal in the city.

The ship’s cannons provided formidable support for the defense against the advance of the Soviet army.

On April 16, 1945, the RAF sent 18 Lancaster bombers from the 617th Division stationed at Woodhall Spa, 225 kilometers from London, to Swinoujscie.

After a few hours of flying, 12 Tallboys are launched rough Lützow.

“One of them did not explode. In fact, one of the pilots, the American lieutenant W. Adams, then reported that he did not see the explosion after he passed “, Laskowski declared for AFP.

One of the Lancaster bombers crashes on Karsibor Island, killing all seven crew members.

Captured by the Red Army, the cruiser Lützow was used as an exercise target by the Soviet Navy and sank in the Baltic Sea in September 1947.