We recently reported on a huge WW2 RAF bomb discovered in Poland. A find such as this is extremely rare, as a relatively small number of these weapons were dropped during the conflict.

The UXB was discovered underwater during dredging works for canal maintenance. 

Polish navy divers planned a five day operation to disarm the munition. The divers were to clear mud and sediment around the bomb, before igniting the explosives inside. It was hoped that the explosive could be burned out, however the weapon ‘high-ordered’.

The risk of a detonation was high and therefore authorities had evacuated everyone within a 1.5 mile radius prior to commencing the operation. Consequently, there were no casualties.

These bombs were filled with Torpex, an obsolete wartime explosive. Many explosives, including Torpex, require a detonation wave created by another explosive charge (such as a blasting cap) to reliably explode. Otherwise, explosives exposed to fire will often just burn instead of high-order (blow up).

Capture3 5,400kg British bomb detonates in Poland during attempt to defuse it
Polish Navy personnel prepare equipment for the operation.

This find appears to be the largest individual piece of UXO found since the recovery of another Tallboy bomb during renovation works on the Sorpe Dam (Germany) in 1958.

On the 6th April 1945, the RAF attacked Swinoujscie (Poland), at the time a Nazi Germany naval stronghold. 617th Squadron aimed 12 Tallboy bombs at the German heavy cruiser Lützow. All the bombs missed however one or two were close enough to sink the ship. And of course one failed to explode.

What type of bomb?

This bomb – dubbed the Tallboy – was second only in size to the RAF’s Grand Slam bomb. At 5.5-tonnes, it was designed to create a seismic shock by detonating a huge charge deep underground. When it initiated, an earthquake effect would shatter the target. As such, it was not designed to strike a target directly.

It was designed to be dropped from an optimal altitude of 18,000ft at a forward speed of 170mph, striking the ground at 750mph. It made a crater 80ft deep and 100ft across and could penetrate up to 16ft of concrete.

The bomb weight and the high altitude required meant that Lancaster aircraft had to be specially adapted. Armour plating and guns were removed to reduce weight, and the bomb-bay doors were modified.

Tallboys were used against several heavily reinforced target types in Poland, Germany and France. These included tunnels, V-1 and V-2 sites, submarine pens, canals, viaducts, and bridges.

These bombs were more than twice the mass of the largest Luftwaffe general purpose ‘iron’ bomb dropped on the UK.

Capture 5,400kg British bomb detonates in Poland during attempt to defuse it
Tallboys at a British airfield bomb dump.