Flame fougasse A flame fougasse ( sometimes contracted to fougasse and may be spelt foo gas ) is a type of mine which uses an explosive charge to project burning liquid onto a target . The flame fougasse was developed by the Petroleum Warfare Department in Britain as an anti - tank weapon during the invasion crisis of 1940 . During that period , about 50 , 000 flame fougasse barrels were deployed in some 7 , 000 batteries , mostly in southern England and a little later at 2 , 000 sites in Scotland . Although never used in Britain , the design was later used in Greece . Later in World War II , Germany and Russia developed flame throwing mines that worked on a slightly different principle . After World War II , flame fougasses similar to the original British design have been used in a number of conflicts including the Korean and Vietnam War s where it was improvised from easily available parts . The flame fougasse remains in army field manuals as a battlefield expedient to the present day . Development history . Following the Dunkirk evacuation in 1940 , Britain faced a critical shortage of weapons . In particular , there was a severe scarcity of anti - tank weapon s , many of which had to be left behind in France . Nevertheless , one of the few resources not in short supply was petroleum oil since supplies intended for Europe were filling British storage facilities . Maurice Hankey then a cabinet minister without portfolio , joined the Ministerial Committee on Civil Defence ( CDC ) chaired by Sir John Anderson , the Secretary of State for the Home Office and Home Security . Among many ideas , Hankey " brought out of his stable a hobby horse which he had ridden very hard in the 1914 - 18 war – namely the use of burning oil for defensive purposes . " Hankey believed that oil should not just be denied to an invader , but used to impede him . Towards the end of June Hankey brought his scheme up at a meeting of the Oil Control Board and produced for Commander - in - Chief Home Forces Edmund Ironside extracts of his paper on experiments with oil in the First World War . On 5 June , Churchill authorised Geoffrey Lloyd , the Secretary for Petroleum to press ahead with experiments with Hankey taking the matter under his general supervision . To this end , the Petroleum Warfare Department ( PWD ) was created and it was made responsible for developing weapons and tactics . Sir Donald Banks was put in charge of the department . The PWD soon received the assistance of William Howard Livens . < ref name = " WO 399 / 19201 " > Livens WH Captain - WO 339 / 19021 . " The Catalogue " , The National Archives < / ref > Livens was well known for his First World War invention : the " Livens Gas And Oil Bomb Projector " , known more simply as the Livens Projector . The Livens Projector was a large , simple mortar that could throw a projectile containing about of explosives , incendiary oil or , most commonly , poisonous phosgene gas . The great advantage of the Livens Projector was that it was cheap , this allowed hundreds , and on occasions thousands , to be set up and then fired simultaneously catching the enemy by surprise . One of Livens ' PWD demonstrations , probably first seen about mid - July at Dumpton Gap , was particularly promising . A barrel of oil was blown up on the beach ; Lloyd was said to have been particularly impressed when he observed a party of high - ranking officers witnessing a test from the top of a cliff making " an instantaneous and precipitate movement to the rear " . The work was dangerous , Livens and Banks were experimenting with five - gallon drums in the shingle at Hythe when a short circuit triggered several weapons . By good fortune , the battery of drums where the party was standing failed to go off . The experiments led to a particularly promising arrangement : a forty - gallon steel drum buried in an earthen bank with just the round front end exposed . At the back of the drum was an explosive which when triggered ruptures the drum and shoots a jet of flame about wide and long . The design was reminiscent of a weapon dating from late medieval times called a fougasse : a hollow in which was placed a barrel of gunpowder covered by rocks , the explosives to be detonated by a fuse at an opportune moment . Livens ' new weapon was duly dubbed the flame fougasse . The flame fougasse was demonstrated to Clement Attlee , Maurice Hankey and General Liardet on 20 July 1940 . Experiments with the flame fougasse continued apace and it rapidly evolved . The fuel mixture was at first 40 % petrol and 60 % gas - oil , a mixture calculated to be useless as a vehicle fuel . A concoction of tar , lime , and petrol gel known as 5B was also developed . " 5B was dark coloured , sticky , smooth paste which burned fiercely for many minutes , stuck easily to anything with which it came in contact and did not flow on burning . " Early flame fougasse designs had a complex arrangement of explosive charges : a small one at the front to ignite the fuel and a main charge at the back to throw the fuel forward . < ref name = " WO 199 / 1433 " > Flame Fougasses - WO 199 / 1433 . " The Catalogue " , The National Archives < / ref > An important discovery was that including magnesium alloy turnings ( the waste product of machining with a lathe ) with the main charge at the rear of the barrel would give reliable ignition without the necessity of a separate ignition charge and its associated wiring . The alloy of about 90 % magnesium and 10 % aluminium was , at the time , known under the Trade name " Elektron " . Design variations . Of the original British flame fougasse designs , there were three main variants : the safety fougasse , the demigasse and the hedge hopper . They all used the same barrels and similar pre - prepared explosive charges . They varied in the details of construction and the amount of ammonal used for the propelling charge . Safety fougasse . The most common form of the flame fougasse was the safety fougasse which was constructed as follows : a barrel of incendiary mixture was placed horizontally in a low position with one round face pointing towards the target . At the back , a section of stove or drain pipe that was blocked off at one end with a thin cover was placed vertically against the rear face of the barrel with the blocked off end a few inches above the bottom . Soil was then built up over the weapon until all that could be seen were the front disk of the barrel and the top of the pipe , which was fitted with a loose cap to keep water out . The main charge was prepared with an electrically triggered detonator in a primer bound with insulating tape to three or four cartridges of ammonal explosive . This assembly was placed in a rubber sponge bag that was , in turn , inside a used cocoa tin ; four ounces ( 100 g ) of magnesium alloy turnings were added , the electrical wires were passed through a small hole in the lid of the tin which was then tightly fitted . The main charges were kept in storage , only to be deployed when enemy action was imminent . Then the cocoa tin was lowered down the pipe at the back of fougasse and tamped down with dry soil before being connected to a firing point about away . Firing simply required the current delivered by a 120 V battery . Private Harold Wimshurst later recalled : The safety fougasse design had the advantage that without the main charge , the fougasse was sufficiently safe that it did not require a guard . Banks records that installing the charge only when the danger was relatively close at hand was a safety feature to protect the public from accidents . The ammonal used for the main propellant charge is a cheap industrial explosive that is notoriously hygroscopic , becoming less effective when it absorbs moisture . Even though the charge was packed into a rubber bag in a tin and sealed with insulating tape , it would not have been a good idea to store it for long in the damp conditions of a flame fougasse installation . Flame fougasses were camouflaged with a covering of light material such as netting – anything heavier would significantly affect the range . They could easily be merged into hedgerows or the banks of a sunken lane within view of a well - hidden firing point . They were placed where a vehicle would be obliged to stop , or at least slow down . The flame fougasse would offer instant and horrific wounds to any unprotected men caught in its fiery maw and would cause a vehicle engine to stop within seven seconds simply because it was deprived of oxygen . British soldier Fred Lord Hilton MM later recalled : Demigasse . The demigasse was a simpler variant of the flame fougasse . It was a barrel of petroleum mixture laid on its side with a cocoa tin charge in a shallow pit just below one of the barrel ' s ridges . On detonation , the barrel would rupture and flip over spilling its contents over an area of about . Left on its own at a roadside , in the open and with no attempt at disguise other than to hide the firing wires , it was indistinguishable from the barrels of tar commonly used in road repair . It was hoped that in addition to the damage done by the weapon itself , experience would cause the enemy to treat every innocent roadside barrel with the greatest caution . Hedge hopper . Another variant of the flame fougasse was the hedge hopper . This was a barrel of petroleum mixture placed upright with a cocoa tin charge containing two primers and just one ammonal cartridge buried in an eight - inch ( 200 mm ) deep pit placed underneath and slightly off centre , but carefully aligned with the seam of the barrel . On firing , the barrel would be projected into the air and forwards , bounding over a hedge or wall behind which it had been hidden . It was difficult to get the hedge hopper ' s propelling charge right , but it had the great advantage of being quick to install and easy to conceal . Home Guard member William Leslie Frost , later recalled seeing a hedge hopper in action . However , placing the hedge hopper so that it worked properly proved difficult to get right and the War Office discouraged its use in favour of the more conventional flame fougasse installation . A further variant of the hedge hopper idea was devised for St Margaret ' s Bay where the barrels would be sent rolling over the cliff edge . Deployment . In all some 50 , 000 flame fougasse barrels were distributed of which the great majority were installed in 7 , 000 batteries , mostly in southern England and a little later at 2 , 000 sites in Scotland . Some barrels were held in reserve while others were deployed at storage sites to destroy petrol depots at short notice . The size of a battery varied from just one drum to as many as fourteen ; a four barrel battery was the most common installation and the recommended minimum . Where possible , half the barrels in a battery were to contain the 40 / 60 mixture and half the sticky 5B mixture . A battery would be placed at a location such as a corner , steep incline or roadblock where vehicles would be obliged to slow . Later development . Although the flame fougasse was never used in Britain , the idea was exported to Greece by a couple of PWD officers when , in 1941 , German invasion threatened . They were reported to have a powerful effect on enemy units . By 1942 , there were proposals for completely buried flame fougasses to be used as oil mines but by then the emergency was over . Almost all flame fougasses were removed before the end of the war and in most instances even the slightest traces of their original locations have disappeared . A few instances were missed , and their remains have been found . For example , the rusty remnants of a four - barrel battery , one of which still contained an oily residue , were discovered in 2010 in West Sussex . Both the Russians and the Germans later used weapons described as fougasse flame throwers or flame thrower mines . They worked on a different principle to the flame fougasse . Fougasse flame throwers comprised a cylinder containing a few gallons of gasoline and oil ; this would be hidden , typically by being buried . On being triggered electrically , either by an operator or by a booby trap mechanism , a gas generator is ignited . The pressure ruptures a thin metal seal and the liquid is forced up a central pipe and out through one or more nozzles . A squib is automatically fired to ignite the fuel . The range of the flame varied considerably , generally just a few tens of yards and lasted only one to two seconds . The German weapons , the Abwehrflammenwerfer 42 , had an fuel tank and were wired back to a control point from where they could be fired individually or together . The flame fougasse has remained in army field manuals as a battlefield expedient to the present day . Such weapons are improvised from available fuel containers combined with standard explosive charges or hand grenades and are triggered electrically or by lengths of detonating cord . In some designs , detonating cord is used to rupture the container immediately before triggering the propelling charge . In order to guarantee ignition , the improvised devices frequently feature two explosive charges , one to throw and the other to ignite the fuel . Weapons of this sort were widely used in the Korean and Vietnam War s as well as other conflicts .