Chemical Warfare

Probably one of the greatest secrets in anti-invasion preparations was the proposed use of chemical weapons. No mention of their use can be found in Home Forces  Defence Schemes, but the Government certainly considered using them. The Chief of the Imperial Staff, Sir John Dill produced the following memo on June 15th, 1940:


“There are strong military arguments in favour of such action {use of chemical weapons}. Enemy forces crowded on the beaches, with the confusion inevitable on first landing, would present a splendid target. Gas spray by aircraft under such conditions would likely to have a more widespread and wholesale effect than high explosives. It can, moreover, be applied very rapidly, and is particularly suitable in an operation where we may get very little warning….

……Besides gas spray, contamination of beaches, obstacles and defiles by liquid mustard would have a great delaying effect. The use of gas in general would have the effect of slowing up operations, and we believe that speed must be the essence of any successful invasion of this country.”


Churchill was in agreement and suggested that Home Defence should be “consulted as to whether prompt drenching of lodgments would not be a great help.”Churchill also stated that employment of chemical weapons would be a cabinet decision.


Britain had a stock of 450 tons of mustard gas – enough for bomber command to spray a strip 60 yards wide and 400 miles long. The Germans would certainly have retaliated and were probably ahead of the British in chemical warfare development . C.I.C Home Forces also noted the limited supply of chemical weapons while the Germans had much larger supplies.


The weapons available for delivering gas in 1940 were:



  • Air spray from tanks (250 lb and 500 lb)

  • Bombs

  • 6” shell (burster chemical)

  • 4.5” shell (burster chemical)

  • 25 pdr B.E

  • Livens projector drums



  • Bulk Contamination Vehicles

  • Chemical Mines

  • Ground bombs (6lb)


All these weapons were filled with mustard (blister gas) except some Livens drums which were filled with phosgene.















         Left: Livens projectors.    Right - Bulk Contamination Vehicle with cylinders ready for release


The most effective method of deploying chemical weapons offensively was considered to be by spray, preferably at night when it could be sprayed at a height of 1,000 to 4,000 ft. Burster chemical shells and Livens drums should be used against specific targets such as strong points in a village where contamination would not be unduly prolonged. Phosgene would have a very limited use due to the danger to civilians.


Deployment of gas defensively would involve the contamination of obstacles and road blocks by ground bombs and mines.  Contamination was to be carried out as late as possible.


A memo of the Director of Chemical Warfare dated Oct 1st 1940 sets out the difference between gas spray and bombs.  Spray was primarily an anti-personnel weapon, designed to cause casualties by contaminating clothes and skin.  Bombs were primarily to be used to contaminate ground, stores and equipment. A 30 lb bomb would heavily contaminate about 50 square yards and lightly contaminate about 300 square yards. It was hoped the deployment of gas would reduce the efficiency of enemy soldiers by 50% by forcing them to wear protective clothing but the Director of Chemical Warfare considered  this very optimistic. One Battle carrying sixteen 30 lb bombs could then contaminate about 800 square yards.


 The considerations of the various options of employment of gas from the air were:

  • As a spray from a low height. Delivered from a height below 1,000 ft. One aircraft could spray effectively a narrow strip of ground 1,000 yards or more in length according to its height and speed and load. On very low level attacks the liquid would fall in a heavy shower and persons caught in it would be thoroughly drenched. Aircraft would be very vulnerable to small arms fire and Anti-Aircraft guns so such attacks would have been combined with machine gun and bomb attacks.

  • As a spray from medium height.  This had the advantage of reduced risk to aircraft. Medium -spray attacks were from a height between 1,000 ft to 4,000 ft. The area sprayed by one aircraft will be larger than the case with low spray, but individual drops would have been further apart and hence the degree of contamination lighter. Aircraft would be vulnerable to Anti-Aircraft guns.

  • As a spray from a high height. High-spray attacks would have been delivered from heights over 4,000 ft. According to the strength of wind and height of the aircraft, the spray may fall in an area a considerable distance down-wind of the aircraft, meaning no or little warning of the attack. The area covered by high-spray attacks would have been considerable - one aircraft could contaminate an area larger than a square mile

  • As a bomb: Best used to contaminate equipment and stores when being landed. Most effective on hard surfaces such as docks and quays.


During 1941 the use of gas was still a possibility in the event of invasion. A memo on the use of gas by the RAF however recommended against its use, instead stating more impact on the enemy would be attained by concentrating entirely on H.E bombing which would have a greater chance of leading to the destruction and defeat of the enemy. It set out the position for the use of gas by the RAF as follows:



• Gas spray – stocks of 250 lb S.C.1 containers sufficient for two squadron sortie loads were stored at Grangemouth, Linton-on Ouse, Hatfield, West Malling and Old Sarum.  There was no reserve stocks so if all the stocks at these aerodromes were used there would be a delay of about one week while cylinders were returned to the filling factory for recharging.

Battles and Blenheims

• Gas spray – stocks of 500 lb S.C.1 containers sufficient for four squadron sortie loads available at Binbrook and Newton for Battles and Wyton and Horsham St. Faith for Blenheims. Some reserves available. A delay of a week if cylinders were sent back to filling factory for recharging.

• Gas bombs – stocks of bombs (50 lb and 250 lb) available at the operational air stations of No.1 and No.2 Groups. Ample stocks of reserve bombs.


• Gas spray – reserve stocks of 1000 lb S.C.1 containers available.


It was not Air Ministry policy to standby to use gas on initial enemy landings. If gas was ordered to be used it would take 24 hours for squadrons to change from a bombing role to gas spray. Furthermore during the change over bombing effort would be reduced by 50%. To use gas on initial landings would therefore require authorization from the Government at least 24 hours before invasion took place. The R.A.F considered that gas spray would only have a harassing effect and would have no stopping power unlike H.E bombs. Its use would not prevent penetration inland by the enemy. If gas spray was to be used it was considered better to use it on ports occupied by the enemy to unload supplies were its effect would be greater on workers rather than fully trained troops.


In 1941 South Eastern Command developed a plan for hindering the maintenance of a German force that had secured a  corridor across The Channel by means of Mustard gas– Plan Y. GHQ instructed Eastern Command in January 1942 to consider if similar opportunities existed in it’s area.  South Eastern Command was also requested to identify other suitable targets in addition to Plan Y.


Eastern Command considered suitable beach targets would be:

  • Beaches which had a strip inland of H.W.M not less than 200 yrds.

  • Reasonable exits

  • A steeper gradient than 1/100.


In Suffolk Eastern Command identified 11 targets requiring 5,692 65lb bombs.


As the requirements put forward by Eastern Command and South Command exceeded the requirement for the original Plan Y the Director of Chemical Warfare noted that bombing of these beaches could not be carried out if stocks were to be maintained for Plan Y, or if bombing of these beaches was carried out then there would be insufficient stocks for Plan Y. The plan was dropped and Commands would instead use the surveys already carried out as a basis to request chemical bombing against specific targets.

































               Above: Map showing targets identified by Eastern Command for gas bombs, Jan 1942

               The number of bombs is for a 65 lb bomb. Orfordness was considered an imortant target

               because of the aerodrome facilities and because it was considered suitable as a place

               to orgainise the landing of supplies etc. Because of the River Alde between Orfordness

               and the mainland, even in 1942 virtually no troops defended this section of coast.


The British continued with chemical weapon development during the war – for example Valley Works, Rhydyumwyn, Wales carried out development and production of chemical weapons, only ceasing production in 1945.



















     Above left and right: Valley Works, Rhydymwyn - part of the works involved in the production of chemical weapons


Chemical weapons testing was also carried out in Suffolk on at least one occasion. On Mar 28th 1943 a 250 lb high explosive / chemical bomb was dropped at Shingle Street, designed to enhance the tactical use of mustard gas by combining both high explosive and gas and hence no need to load seperate high explosive and chemical bombs. The test was a failure as the instantaneous fuse required to prevent the chemical charge being buried in the ground reduced the effectiveness of the high explosive.




The Bodies on the Beach - Sealion, Shingle Street and the Burning Sea Myth of 1940, J Hayward, CD41 Publishing, 2001 – Valley Works, Rhydymwyn

Military Organization for the Defence of United Kingdom, Northern Ireland, Orkneys & Shetland, Iceland and the Faroes, Air Ministry papers, TNA

Chemical Weapons, TNA

Protection Against Gas and Air Raid - Pamphlet No 1, Protection Against Gas in the Field, HMSO, 1939


10 6 gas targets DSCF3523 DSCF3522