A 12,000-pound WWII-era bomb exploded in a shipping canal outside the Polish port city of Swinoujscie on Tuesday, sending a plume of water high into the air as a team of naval divers worked to neutralize it from a distance.
No one was injured in the operation, which the Polish Armed Forces considered a success, as the ammunition, a British “Tallboy” bomb, was ultimately destroyed.
The day before the operation, the Polish Ministry of Defense announced that the bomb was the largest ever discovered in the country and that divers from the Polish Navy’s Eighth Coastal Defense Flotilla would attempt to remotely neutralize the weapon through a process in which Special charges are carried out.Used to pierce holes in the thick steel casing of a bomb and set the explosive material inside on fire.
If this had been successful, the process would have enabled the 5,200 pounds of energetic material in the bomb to burn out safely underwater so that divers could lift the deflated shell out of the water or drag it further out to sea.
According to experts from the International Committee of the Red Cross, Poland has removed explosive remnants of war from its territory since the end of World War II. From 1944 to 2003, more than 96 million pieces of explosives were removed at an estimated cost of $ 866 million, and from 1944 to 1989 unexploded ordnance claimed the lives of more than 4,000 people in Poland.
In the field of bomb disposal, any procedure for securing ammunition also carries the risk of the object exploding, regardless of how precisely and properly these procedures are followed.
With a bomb like this one, divers would most likely have examined the ammunition underwater, taken measurements, and carefully sketched key identifying features. Analyzing their results on land, the divers would find out what types of fuses are normally attached to such a bomb and examine documented procedures to remove or safely destroy them without the ammunition exploding.
However, sometimes such steps are impossible. If the fuse is inaccessible due to deformation on impact or other obstacles, bomb disposal experts can attempt a process called deflagration, which involves cutting into the bomb and setting fire to the explosive material inside to safely burn itself out. But fast-burning explosives that are still in a thick steel case can still explode, even if additional holes are made to vent the gases created by the fire.
The Department of Defense also said the operation was the first attempt to neutralize a Tallboy bomb underwater. The ministry did not respond to messages asking for comment and efforts to reach the Polish embassy in Washington were unsuccessful.
The Tallboy was designed by the Royal Air Force in 1943 and was mainly used for attacks on high value targets such as submarine pens, viaducts and bridges, as well as on launch sites for the V-1 cruise missiles and V-2 missiles used to terrorize civilians England during the war. According to a report by Wing Cmdr. John A. MacBean and Maj. Arthur S. Hogben, 95 Tallboy bombs, were also dropped on ships such as the German cruiser Lützow, which moored in Swinoujscie in 1945.
The authors attribute Tallboy bombs to the sinking of the German battleship Tirpitz off northern Norway in November 1944. When tallboys fell on land, they often created craters 85 feet in diameter and 25 feet deep. It was the second largest bomb used by British forces during the war, after the 22,000 pound Grand Slam ammunition that was also dropped on German targets. Together, the Tallboy and Grand Slam were known as “earthquake bombs” for the devastation they caused on land.
The ammunition, which was destroyed by divers on Tuesday, is said to have been dropped on the Lützow, but could not explode on impact. Wing Commander MacBean and Major Hogben said the bomb’s fuse was designed to blow up the bomb after a delay of just a few hundredths of a second. In this instance, however, it apparently failed during the attack, leaving the 21-foot-long bomb immersed in the mud under 33 feet of water for three quarters of a century.