Here we reveal the story behind an unexploded secret Second World War "Bunker Buster" recovered from the roof the V" bunker at Eperlecques in France.
On 22 December 1942, Hitler ordered that the construction of a series of enormous reinforced concrete bunkers to facilitate the launching of the new V2 rockets should begin immediately. Within a matter of weeks the site of the first of these structures was chosen – in the Forêt d’Eperlecques, just thirty minutes south of Calais.
Building work began in March 1943, and was initially scheduled to take a matter of months. Reports from the Resistance and the obvious deforestation of a large area of woodland soon brought the site to the attention of the British authorities. Initially, uncertainty surrounded the reason for structure’s construction – one idea suggested that it was a new power station. Eventually, however, the fact that the bunker was in some way associated with the V2 rocket became apparent. Eperlecques had suddenly become a priority target.
It is from the roof of this ‘target’ that French bomb disposal officers have recently recovered an unexploded Second World War British rocket-assisted bomb. The bomb was initially found two or three years ago protruding from the massively thick concrete roof of the bunker. But it was not until the last two weeks of January 2009 that work to recover the device could begin.
The recovery itself was no simple task. The easiest method of accessing the roof of the bunker was, as you can see in the photographs here, by helicopter!
From what has been established before and after recovery, it would appear that the device is an extremely rare example of a British rocket-assisted bunker-busting bomb that was known as the ‘Disney Bomb’ - the invention of a British naval officer, Captain (later Lieutenant-Commander) Edward Terrell RNVR. Terrell, a barrister in civilian life, and who was part of the Admiralty’s Department of Miscellaneous Weapon Development (more commonly referred to as the DWMD or ‘Wheezers and Dodgers’), had designed the bomb to be to be used against super-hardened armoured or concrete reinforced targets such as U-boat pens.
Each bomb had a streamlined hardened case and weighed some 4,500lbs - two tonnes. Designed to be dropped from 20,000ft, a tail mounted set of rocket motors would be ignited at 5,000ft by a barometric fuze, accelerating the weapon to a high impact velocity. Interestingly, however, one report states that the impact velocity was about 2,600km/hr - substantially less than the reported 4,000km/hr achieved by the non-rocket assisted 12,000lb Tallboy bombs (which were also dropped on the bunker at Eperlecques).
The forged and hardened steel cylinder body, which is what can be seen in our pictures, with its sharply pointed nose, contained about 500lbs of the extremely sensitive explosive Shellite (a British explosive filling for armour-piercing naval shells from the 1920s and 1930s). In the base of the bomb were mounted two British No.58 pistol fuzes.
The tail unit containing the rocket motors, no longer present on the Eperlecques example, was attached to an adapter plate which in turn fitted to the base of the bomb. For the technically minded, each tail unit contained nineteen 3-inch rockets, packed together and weighing about 900lbs. Each individual motor contained 12.5lbs of cruciform shaped flashless cordite rocket propellant.
Terrell had designed the ‘Disney Bomb’ to be fitted to external racks, and in British use it would have been carried to the target by Avro Lancasters. Whilst at least one contemporary photograph does exist that appears to show a ‘Disney Bomb’ fitted to Lancaster – mounted externally to an under wing bomb rack between the inboard engine and fuselage – all the evidence points to the fact that it was never dropped in anger by the RAF.
Indeed, it would seem that the ‘Disney Bomb’ was first deployed by the USAAF’s 92nd Bomb Group on 14 March 1945. The target was the concrete E-boat or U-boat pens at IJmuiden in northern Holland. Each of the nine B-17 Flying Fortresses involved carried one ‘Disney Bomb’ under each wing, and on that occasion a single direct hit was reported. A total of 158 ‘Disney Bombs’ were used operationally by the end of hostilities in Europe.
It is believed that the ‘Disney Bomb’ at Eperlecques was dropped, by a B-17 of the 92nd Bomb Group, to test the weapon’s effectiveness after Canadian troops captured the site on 6 September 1944.
An initial assessment of the Eperlecques ‘Disney Bomb’ by French EOD officers suggests that the two No.58 fuzes had both failed. At the time we closed for press, it had not been possible to confirm whether this particular bomb was charged with explosive or an inert filler. Much of the examination of the device, described as being “in perfect condition”, has been hindered by the fact that the ‘Disney Bomb’ was a closely guarded wartime secret. So secret in fact, that even now, over six decades after the end of the war, any files relating to its design and manufacture remain classified and closed to public inspection.
With the bunker having been open to the public since 1974, one can only speculate exactly how many visitors have strolled through the museum, oblivious to what was embedded in the roof above their heads!