A Short History of Royal Engineer Bomb Disposal

A Short History of Royal Engineer Bomb Disposal Including that of 33 Engineer Regiment (EOD), the Reserve Army and Territorial Army Units By Lt Col E.E. Wakeling ERD The first bombs to be dropped on the U.K. were at Hoy, in the Orkneys in October 1939. The first unexploded bombs fell on the Shetlands in November 1939. The four bombs were recovered by the RAF based at Sullom Voe. They were 50kg and had penetrated to a depth of between six to ten feet. It was soon realised that any bomb dropped i
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  A Short History of Royal Engineer BombDisposal   Including that of    33 Engineer Regiment (EOD), the Reserve Army and Territorial Army Units   By Lt Col E.E. Wakeling ERD  The first bombs to be dropped on the U.K. were at Hoy, in the Orkneys in October 1939. Thefirst unexploded bombs fell on the Shetlands in November 1939. The four bombs were recovered by the RAF based at Sullom Voe.They were 50kg and had penetrated to a depth of between six to ten feet. It was soon realised thatany bomb dropped in an urban area would have to be immunised and could not be blown up insitu.The fuzes were sent to the Research and Experimental Branch of the Ministry of Supply whodiscovered that they were E.C.R. (electrical condenser resistance). This august body, apart fromfinding out how each new fuze discovered, worked and developing a method of immunising alsodesigned the necessary equipment and authorised its manufacture.These first fuzes were all No (15) and it was discovered that they could be immunised merely bydepressing the plungers, in the top of the fuze, a few times. This allowed the electrical charge inthe firing condenser to leak back to earth, thus making it inert ± and safe. This simple method of immunising did not last long as the Germans brought out a No (25) fuze. Very similar to the No(15) ± an impact fuze ± but they had changed the internal circuit a little so that when the plungerswere depressed the bomb exploded.The range of bombs which the Germans had at that time were in three types:-50 kg (112 lb) S.C. or S.D.250 kg (550 lb) S.C. or S.D.500 kg (1,000 lb) S.C. or S.D.1,000 kg (2,400 lb) S.C. (Herman)1,000 kg (2,400 lb) S.D. (Esau)1,400 kg (3,200 lb) S.D. (Fritz)1,800 kg (4,000 lb) S.C. (Satan)S.C. stood for Spreng Cylindrisch, a thin walled, general purpose bomb.P.C. stood for Panzerdurchsclags Cylindrisch and was a heavy armour piercing bomb.The latter used almost entirely against shipping and heavily shielded targets.The weight ratio of the two most used types were S.C. fifty five percent explosive, whilst theS.D. had thirty five percent.  Later in the war they introduced the Flam 250 and Flam 500. These were the same size as their equivalent in S.C. but were filled with a flammable oil mixture which was spread over a widearea when the three pound burster charge exploded. They were designed to start a fire over awide area, but frequently just covered it with its disgustingly smelly contents. They also similarlyfilled S.C. bomb cases with the same results. All of these had simple impact fuzes. Manyµcontainers¶ ± of incendiary or anti personnel bombs ± were shaped in a bomb form, presumablyto fit into the existing bomb racks. The µButterfly Bomb¶ was srcinally contained in an A.B. 23,which was, more or less, the same shape as a 50kg bomb and contained 23 bombs, hence its title.It had an air burst fuze so that the container opened up soon enough for the bombs to armthemselves before reaching the ground.Unlike bombs from any other country in the world, which used µnose¶and µtail¶ fuzes, the Germans had theirs set in the side of the bombcasing, with a cylindrical fuze pocket running across the diameter of the bomb. The fuze was correctly positioned by a locating ring andheld in place by a screwed locking ring. Into the base of the fuze wasscrewed a µgaine¶, about one inch in diameter and one and a half inches long. This contained a high explosive called Penthrite Wax.Around the gained was a hollow pellet of picric acid, the remainder of the fuze pocket was filled with solid pellets of picric acid.When the German armourer loaded the bombs in the aircraft, heclipped a µcharging head¶ on the boss of each fuze. The head had twoµspikes¶ which depressed the plungers in the fuze boss. (There wereoften two separate firing circuits in a fuze.)When the bomb aimer pressed the release button, the bombs were unhooked and as they droppedout of their racks a charge of electricity was passed through the charging head into each fuze.The charging heads were on telescopic arms, thus allowing time for the electricity to flow, beforedisconnecting themselves at the extent of their arms. The electricity first flowed into theµreservoir¶ condenser, then it passed through a resistance, slowing down the flow before reachingthe µfiring¶ condenser thus allowing time for the aircraft to reach a safe distance before the bombs became µlive¶. The electrical charge then remained in the firing condenser until the bombhit the ground. The shock activated a trembler switch which allowed the electricity to flow intothe firing bridge which set off the detonator.The exploding system was that when the detonator in the fuze was fired a flash from it travelledthrough an aperture into the penthrite wax which then exploded, setting off the picric acidfollowed by the main bomb filling, usually of TNT (tri nitro toluene.)When a B.D. officer extracted a fuze, the first thing he did was to remove the gaine from thefuze. The metal of the gaine and the penthrite wax contained therein was sufficient to severelymaim or kill should it explode, even away from the bomb.  The first two pieces of equipment produced for the B.D.officer were the µCrabtree¶ discharger. A simple devicewith two spikes which depressed the plungers in thefuze, when applied. It could be screwed on to the fuze boss and it had a ring fitted in its top to which a piece of string could be tied, thus allowing the B.D. Officer toextract the fuze from a safe distance. When the No (25)fuze was introduced, the two spikes were removed andthe Crabtree was still used to extract the fuze. The other  piece of equipment was the µUniversal¶ fuze key. Thisconsisted of a steel bar about twelve inches long withtwo adjustable lugs that could be fitted into the twoslots of a locking ring. As it was discovered that thelocking rings were standard, no adjustment was needed.Subsequently, a much better fuze key was designedwith fixed lugs. By the end of 1940 another piece of equipment was designed, known as theµSteam Sterilizer¶. Its purpose was to circumvent the fuze by emptying the bomb of its explosive.However it required either the base (filling) plate to be removed or a hold cut in the bomb casing.Both of which activities would probably have activated the fuze. However, it was used to mucheffect later in the war when, whilst the fuzes had been immunised their extraction would haveresulted in the bomb exploding. In which cases the contents were steamed out and the explosioncaused by the setting off the fuze pocket(s) was of a small size and minimal damage was done. Top  In spite of the fact that in the µmid 1930s, there had been a war raging in Spain, in whichGermany was very involved, giving their airmen much practise and a change to evaluate their  bombs and fuzes. Intelligence of the Spanish bombing was common knowledge, in fact theinformation was available to anyone who cared to ask, from H M Stationery Office.Munich, in 1938, concentrated the minds of our Government, but they thought along the lines of Civil Defence precaution, shelters, gas, evacuations, emergency services, etc. Little or no thoughtwas given to Bomb Disposal at the time.The worst omission was that details of the German E.C.R. fuzes had been granted a patent by theU.K. patents office as far back as 1932. Yet we had to wait until November 1939, when the firstunexploded bombs were available for research.At first it was thought that the Home Office should be responsible had it was planned thatmissiles should be collected by ARP wardens and taken to a suitable dump. To be disposed of later, probably by the army! No one in the Home Office sought advice from the RAF who couldhave told them of the impossibility of the suggestion.  Proposals were made for specialist teamsof ARP which should be trained andequipped for the work, but no decisionswere taken by µhigher authority¶ toimplement it. Instead the War Office wasasked to provide teams until the ARPteams could be trained. It was decided bythe War Office that the Royal Engineerswould provide the teams, which wouldconsist of an NCO and two sappers their  job being to dig down to the bomb and blow it in situ! It was also their job totrain the ARP teams but the civiliansfailed to materialise. There was not a lot of work for the R.E. teams and they almost becameanother lost army for this was the period of the phoney war of Sept. 1939 to April 1940. Duringthis time there had been sporadic invasion of our air space during which a few bombs weredropped. It was the result of these raids with a few unexploded bombs, which were immunised,that more though was given to the coming problem. It was finally realised that a properlyorganised, disciplined force would be needed and on 2nd February 1940 the army formally took over the responsibility for Bomb Disposal in the U.K. ± Apart from bombs which fell on Royal Navy or Royal Air Force property. The Navy also became responsible for all missiles which fellinto estuaries below the high water mark.The first authorised establishment for Bomb Disposal ± Formation Order of May 1940 ± createdtwenty five sections, each of a Lieutenant, a sergeant and fourteen other ranks. The srcinal bomb disposal working parties were absorbed within the new organisation.It is one thing to authorise the formation of units, but it is another to find the men, equipment andtransport. All of which were in short supply. The sections were issued with standard R.E. storessuch as hammers, chisels, blocks and tackles, picks and shovels plus a small amount of explosives. B D equipment was still almost non existent.In the event of the organisation was unworkable. Although belonging to the Corps of RoyalEngineers, they were µWar Office¶ controlled ± by a department called the Inspector of Fortifications, headed by a Royal Artillery General. Fortunately, the Minister of Supply formedan Unexploded Bomb Committee, whose purpose was to consider all problems relative to bombdisposal.By the end of June 1940 it came apparent that the twenty five B D sections already formedwould in no way be able to cope with the expected deluge of bombs that would result from thewithdrawal of our forces through Dunkirk and elsewhere. Another 109 B D sections wereauthorised. Volunteers were called for and a few came forward. In the main the Other Rankswere just µposted in¶. Most of the young officers came straight from a Royal Engineers OCTU(Officer Cadet Training Unit.) Some had received an immediate commission as a result of their technical or professional qualifications. All ranks were informed that they could, after six monthsservice in bomb disposal, elect to transfer to another branch of the Royal Engineers. This offer 


Nov 4, 2017


Nov 4, 2017
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