Divers Tried To Defuse Poland’s Largest WWII Bomb – But Then Disaster Struck

Shockingly, the bomb had been hiding in plain sight for 75 years – hauntingly close to the people living in the Polish city of Świnoujście. It was dropped in WWII, when Britain’s famed Dambuster bomber squadron launched a brutal attack on a German ship moored off the coast. And while the majority of the explosives hit their mark, this one sank – undetonated – to the bottom of the canal.

You’d think living near any type of dormant explosive would be enough to jangle the nerves. But this is no ordinary weapon that threatened the population of Świnoujście. Beneath the waters of the Piast Canal lurked a sleeping Tallboy – a device popularly known as an earthquake bomb. And believe us, the explosive is suitably named.

The Allies dropped more than 850 Tallboys on enemy targets during WWII – wreaking widespread devastation across Europe. Yet not all of the bombs exploded on impact. And in 2019 one was discovered during work on the Piast Canal, which sits beside the German border. Military divers then began the painstaking process of defusing the bomb – though, as we know, the process didn’t go to plan.

Yes, three quarters of a century after it was dropped, the bomb beneath the Piatz Canal exploded – just as the experts were working to defuse it. And in the aftermath of the devastating eruption, there was one question on everybody’s lips: how did the device remain so powerful after so many years?

The answer lies in the work of the famous British engineer Barnes Wallis. Wallis began his career designing the airships and airplanes that characterized the early days of flight. But when WWII broke out in 1939, he decided to apply his talents to the art of combat instead. A proponent of tactical bombing, the expert believed that the development of devastating explosives would be key to defeating the Axis forces.

Creative and ambitious, Wallis dedicated himself to developing technology that would help bring the Axis powers to their knees. When the British government set its sights on destroying German dams, for instance, the engineer was determined to figure out the best approach. But the chosen target – the Möhne Reservoir some 30 miles outside Dortmund – posed a big challenge.

The dam that the Allies wanted to attack stood around 130 feet tall and was in places more than 100 feet thick. Even so, the eponymous engineer came up with a plan to breach the structure – using little more than a volley of large explosives. But hitting the target from the sky would have been practically impossible. And so the idea of an attack on Möhne was shelved.

Though Wallis would not take no for an answer and continued to dream up plans for a feasible attack. If the explosives could not be dropped from above, he reasoned, perhaps they could be skimmed across the water towards the target? By experimenting with marbles, the engineer eventually came up with the idea of a bouncing bomb.

Although it might have sounded ridiculous, Wallis’ idea worked. And the plan to launch an attack on German dams was back on the table. Just after midnight on May 17, 1943, the Royal Air Force No. 617 Squadron dropped a series of bouncing bombs above the Möhne Reservoir. Eventually, they succeeded in breaching the massive structure.

Later, the squadron also managed to bomb a hole in the Edersee Dam – some 80 miles south-east of Möhne. Thanks to Wallis’ weapons, German resources were directed towards rebuilding destroyed infrastructure and away from the war effort. And even though more than 1,500 innocent civilians died, the attacks are generally viewed as heroic today.

The Dambusters’ attacks secured Wallis’ reputation, too. And this enabled him to revisit ideas that had initially been rejected. Among these was an invention dubbed the earthquake bomb: a large explosive designed to burrow deep below the target and detonate underground. Afterward, the engineer believed, the shockwave would create widespread devastation.

Wallis originally envisaged a huge, ten-ton bomb that would be dropped on the enemy from a height of 40,000 feet, his foundation explained. But this scheme was too ambitious for the technology available at the time. Instead, he settled for an explosive weighing six tons – designed to be released from 18,000 feet.

Given the nickname Tallboy, Wallis’ ambitious new weapon was first put to the test in France on the night of June 8, 1944. The target was the Saumur railway tunnel – a vital lifeline connecting southern and northern France. Just days earlier, the Allies had landed on the beaches of Normandy, and the bombers were tasked with cutting off access to the invasion site.

The 617 Squadron would be about to make history once again as it took to the skies over the Loire with 19 Tallboy bombs. And sure enough, its mission devastated the railway line and stopped German troops from being able to travel north to fight off the Allies. From that point onwards, Wallis’ invention played a central role in the British war effort – destroying targets across western Europe.

Yes, as WWII progressed, the Allies dropped hundreds of Tallboy bombs on enemy targets – destroying buildings, battleships and infrastructure alike. It eventually became obvious that the Axis powers were going to lose. But the conflict across Europe would continue for nearly a year after the Allied invasion of northern France. And in countries like Poland – where the unexploded device would later be discovered – the fighting was particularly fierce.

In mid-January 1945 the Soviet Union had begun its advance into Poland – prompting a mass exodus of German citizens. And by March many of them had gathered in Świnoujście on the north-west coast. Before the refugees could escape across the Baltic Sea, though, the United States Army Air Force launched a brutal attack and thousands of civilians were killed.

Despite relentless assaults from the Allies, the Axis powers continued to fight. And on the Piast Canal outside Świnoujście, the German cruiser Lϋtzow was deployed as part of a last-ditch effort to hold off the Soviets. But the Nazis suffered a serious blow on April 16, 1945, when the Dambusters carried out yet another devastating aerial attack.

This time, the 617 Squadron dropped 12 Tallboys from Lancaster bombers onto the anchored Lϋtzow. Things didn’t exactly go to plan. According to reports, one of the aircraft got into difficulties and ended up crashing on nearby Karsibor Island. And if that wasn’t bad enough, one of the explosives failed to detonate – sinking dormant into the Piast Canal. That one would come back to bite, though, as we already know.

One of the other Tallboys did manage to land directly on the Lϋtzow, while several others landed close to the mark. Having sustained extensive damage in the blasts, the vessel sank to the bottom of the canal – leaving just its deck jutting out above the water. For weeks afterward, the Germans continued to use this exposed section as a gun turret. But ultimately, the ship was later scuppered and sold as scrap.

Less than a month after the Dambusters’ attack on the Lϋtzow, Germany surrendered, and the war in Europe finally came to an end. The bombs dropped over the Piast Canal, as it turned out, would be among the last Tallboys ever deployed. But the story of Wallis’ deadly explosives did not end there.

Fast forward almost 75 years, and Świnoujście has become a popular tourist resort. Instead of refugees desperate to flee across the Baltic Sea, the city is filled with people enjoying relaxing holidays by the coast. Yet in September 2019 workers discovered something that would shatter this peaceful idyll and bring back the horrors of WWII.

That month, a project was underway to deepen the waterway outside Świnoujście. But as the canal was being dredged, a long-forgotten secret emerged – the unexploded Tallboy that had been dropped on the Lϋtzow during the war. It was reportedly the biggest dormant WWII device ever discovered in Poland, so it must have been a startling sight. But would the bomb still pose a risk to the public so many years after it had been dropped?

For almost a year after it was discovered, the Tallboy remained at the bottom of the Piast Canal – its existence looming ominously over the city. Then in October 2020 work to defuse the dormant bomb finally began. But before experts could start the painstaking work, they needed to secure the area. And according to CNN, that meant temporarily turfing over 750 people from their homes.

Perhaps unsurprisingly, many of the residents of Świnoujście were taken aback by the extreme measures. Speaking to the AFP in October 2020, local Halina Paszkowska said, “I’ve lived here 50 years, and there have been other bombs. But this is the first time there’s an evacuation! Before, we just had to stay indoors.”

In fact, some people living in the city told reporters that they were going to ignore the evacuation orders. But as experts prepared to defuse the 20-foot bomb – which contained around 2.5 tons of explosives – fear began to spread through the community. And in the end, most people left their homes and took shelter in centers nearby.

On October 12, 2020, a team of sappers from the Polish Navy swam out into the Piast Canal – determined to tackle the dormant bomb. Initially, the plan was to spend the first part of the five-day mission carefully preparing the explosive. Speaking to the press at the time, military spokesman Grzegorz Lewandowski explained, “It’s a very delicate job… The tiniest vibration could detonate the bomb.”

But why did the Polish Navy need to defuse the bomb at all? Plenty of leftover WWII explosives have simply been detonated in controlled situations and haven’t needed to be meticulously dismantled. Well, according to Lewandowski, the nearby bridge meant that this wasn’t an option in Świnoujście.

And so the divers decided to use a method called deflagration, which involves simply burning off the explosives without a detonation. By using a remote-controlled device to heat the bomb, they could render the Tallboy inactive without needing to be anywhere near the weapon. This, of course, must have been somewhat reassuring. Still, experts were apparently only 50 percent sure that the operation would be a success.

As it turns out, they were right to err on the side of caution. On October 13 – just one day after the operation began – the Tallboy exploded, sending a jet of water into the skies high above Świnoujście. And had any of the team been closer to the blast, they would likely have met a violent end.

But despite the dramatic appearance of the explosion, experts insisted that the operation had been controlled. The following day, Lewandowski made an announcement on the Ministry of National Defence of the Republic of Poland’s Twitter account. It read, “The deflagration process turned into detonation. The object can be considered neutralized. It will no longer pose a threat to the Szczecin-Swinoujscie shipping channel.”

Around the same time, an unnamed spokesperson for the Polish military told CNN, “Every step of [the] operation was under control.” But what was the impact of exploding Wallis’ earthquake bomb in the middle of a built-up area? Thankfully, reports claim that nobody was hurt in the aftermath of the detonation. Phew!

There was apparently no damage to nearby buildings, either. And while online commenters speculated on the potential harm to marine life, there appeared to be no evidence of any ill effects springing from the incident. And before long, life in Świnoujście returned to normal.

But this wasn’t the first time that a long-dormant Tallboy has reared its head long after the end of WWII. Back in January 1959, some 650 residents of Langscheid in West Germany were evacuated from their homes after an earthquake bomb was discovered at the bottom of a reservoir. Ironically, the same organization that had dropped the bomb was called to sort it out.

That’s right: fifteen years after the Royal Air Force unloaded the Tallboy over Germany’s Sorpe Dam, a British flight lieutenant helped to defuse it. And if reports are to be believed, he succeeded – this time without causing an explosion. At the time, it was one of the biggest explosives ever tackled by any bomb disposal unit.

To date, the bombs found in Langscheid and Świnoujście are the only unexploded Tallboys to be unearthed. Yet the former battlegrounds of WWII are littered with leftover ordnance even today. Some of these devices have detonated dramatically over the years, though others may yet be lingering, undiscovered, beneath the ground.

On June 23, 2019, for example, residents of Limburg in Germany reported hearing a loud explosion during the night. And when they awoke, they saw that a huge crater had appeared in a nearby field. On closer inspection, it was revealed that an old WWII bomb had exploded – tearing a hole that New Scientist says was more than 30 feet wide.

Luckily, none of these incidents resulted in anything worse than a bad shock for those in the vicinity. But things haven’t always worked out quite so well. In 2014, for instance, construction workers in the German town of Euskirchen accidentally triggered a dormant WWII bomb. Sadly, one man died in the explosion that followed.

But you can breathe a sigh of relief, as experts usually know exactly what to do when it comes to defusing old bombs. And it happens more often than you might think. As recently as 2019, some 2,000 people were cleared from the streets surrounding Paris’ Porte de la Chapelle train station while experts tackled a 75-year-old explosive. And in 2017 a device found at Frankfurt’s Goethe University prompted 70,000 citizens to relocate. It was Germany’s biggest mass evacuation since WWII.

Luckily, explosions like the one Świnoujście are few and far between. But with hundreds of Tallboys dropped over Europe during WWII, can we really be sure that all of them are accounted for? Or might there be another deadly surprise just waiting to be discovered? Let’s hope not, eh?