During the early stages of the Second World War, it began to look more and more likely that the Germans would stage a full-on invasion of Britain – the first invasion of the island by a foreign foe in hundreds of years. In preparation for the coming invasion, Britain’s Home Guard began to set up a number of defenses.
One such defense was the terrifyingly effective flame fougasse – essentially barrels of petroleum and oil that, when detonated, would engulf enemy tanks or armored cars in ferocious fireballs as large as 50 square yards in area.
The idea of the flame fougasse did not originate in the Second World War. Instead, the use of similar weaponry goes as far back as the sixteenth century, when fougasses were invented. These early fougasses were crude but effective (when they worked), and basically consisted of a large hole or hollow dug in the ground which was filled with gunpowder and projectiles like rocks or scrap metal.
These primitive fougasses were ignited by a rudimentary black powder fuse, which could be risky to the man igniting it, and which generally gave away the position of the fougasse to the enemy. However, in later centuries the fuse was modified so that it could be ignited by flintlock, and later by tripwire mechanisms, effectively turning fougasses into the first anti-personnel fragmentation mines.
Fougasses saw a good deal of use throughout a number of wars in Europe, as well as the Revolutionary War and the Civil War in America. However, it was not until the Second World War that the fougasse concept was refined and made into a far more effective and reliable form of weaponry.
For the purpose of defending Britain against invading German forces, who would no doubt come with a large force of tanks and armored cars, the flame fougasse – a fiery refinement of the centuries-old fougasse concept – would prove a potent and effective means of defence, in tests conducted by the Home Guard, at least.
Developed by the British Petroleum Warfare Department, the flame fougasses with which the Home Guard intended to defend Britain were initially filled with a mixture of 25% petroleum and 75% oil, which later was changed to 40% oil and 60% petroleum, inside a 40-gallon steel oil drum.
Detonation of this highly flammable mixture was achieved with ammonal, an explosive made from aluminum and ammonium nitrate. Larger 50-gallon drums were also used, and an improved mixture of lime, tar and a different type of petroleum later replaced the 40/60 oil and petroleum mix.
When detonated, the fireball generated by the explosion was formidable to say the least; covering an area of up to 50 square yards per barrel. The heat of the flames was beyond intense, and any unfortunate invader caught in the raging torrent of fire would be dead within seconds.
Those who were in tanks or armored cars, even if shielded from the flames would likely be roasted alive inside their vehicles as the heat turned the steel boxes into ovens.
In order to increase the effectiveness of these weapons, they were strategically placed in areas where approaching vehicles would be forced to either stop or slow down. As such, they were often hidden in banks on the side of the road where there were sharp bends, steep inclines, o other geographic features that would cause vehicles to have to slow down.
As the target vehicle passed the flame fougasse, it would be detonated by a person nearby hiding behind cover, who activated the fuse.
The detonator was the weak point of the flame fougasse. Because ammonal – a cheap, easily-produced industrial explosive – is easily damaged and rendered ineffective by moisture, whoever was manning the flame fougasse installations (which usually consisted of four barrels used together) would have to wait until the enemy was fairly close before inserting the detonator.
In preparation for the expected German invasion, around 50,000 flame fougasse barrels in approximately 7,000 different installations were set up all across Britain. Fortunately, the German invasion of the British Isles never happened, and none of the flame fougasses in Britain were ever used in combat.
The concept of the flame fougasse was a crude but effective one, and while not guaranteed to stop a German invasion in its tracks, it certainly would have impeded an invading force and probably taken out a good number of tanks and other military vehicles.
The concept of the flame fougasse was also used by Soviet forces during the Second World War, most notably in the defense of Stalingrad. The Germans had their own version, called the Abwehrflammenwerfer 42, but this was far smaller and different in design to the British flame fougasse.
The design for the flame fougasses that Britain intended to use during WWII was improved over the years, and flame fougasses were used in later conflicts, such as the Korean War and the Vietnam War. Designs for flame fougasses are still, in fact, part of the current British battlefield manual, Combat Flame Operations. Hopefully, however, flame fougasses will never need to be put into action.