The term of 'The fog of war' was used in the context of the Great War as it had been in previous wars. But in the former wars it was also an allusion to the grey-black gun powder smoke produced by cannons and rifles that quickly obscured the battlefield as the shooting began, and hid foe and friend alike

In the Great War, the smokeless propellants that had been developed during the early years of the 20th Century largely alleviated this problem; although residual smoke clouds from some projectiles still occurred i.e. the black woolly smoke produced by the much feared heavy German 'Jack Johnson' shells.

Another form of obscuring of the battlefield in the Great War was by the clouds of toxic gas, which varied from billowing white to sulphurous and greenish-white.

For the first time in history, war was, in today's terminology, a 24/7/52 event. In earlier wars battle was strictly a daylight activity that began at dawn and ceased at nightfall, and rarely lasted that long. As late as 1815 the Duke of Wellington at Waterloo was declaiming "Night or the Prussians must come". In the Great War the belligerents sought to turn night into day so the battle could continue without cease. Light was key element in the continuous battle of defence and offence and man-made smoke was the big obscurer.


In late1914, an initially reluctant German High Command was convinced by Fitz Haber, a famous German chemist and Nobel Prize winner that a short cut to victory was to use poisonous gas on the battlefield. Haber's motivation for this drastic and illegal action was his serious doubt that the German chemical industry could keep up with the Allies in the production of explosives in the long term. If German industry failed, the war would be surely lost. A strictly non-military person, Haber seemed to develop a remarkable, almost hypnotic, effect on the military elite.

After two unconvincing efforts at Bolimov, on the Eastern Front and at Neuve Chapelle, in France, on the 25th April 1915, the German Army, under the direct instruction of Fritz Haber, successfully released against the French on the Western Front clouds of highly toxic chlorine gas.

Due to the general shortage of shells at the time, this obvious option of delivering the gas was replaced by the use of pressurised steel cylinders. The gas was piped forward from 6,000 of these cylinders containing liquefied chlorine that were ranged along their trenches in the Langemarck Sector of the Ypres salient. Blown as a greenish cloud towards the Allied lines by the wind, the chlorine gas slowly swept across the trenches occupied by French colonial troops causing panic and many casualties. But such was the startling effect, even the Germans themselves were surprised and unprepared: they had insufficient reserves and no means of protecting themselves from the effect of the gas i.e. no protective masks or clothing.

So, despite making considerable initial territorial gains, the Germans were unable to take full advantage of the ensuing disorganisation of the Allies. And any immediate tactical opportunity was lost. Other attacks on the Allies quickly followed but, with amazing resourcefulness and courage, the shock effects of the gas were resisted. Thereafter, the Allies' line was largely held against toxic gas attacks until elementary, but increasingly effective, anti-gas measures could be implemented and the initial shock-effect of the toxic gas largely neutralised. All this despite the German's release of a deluge of chlorine gas from 20,000 cylinders (500 tons) over a period of only four weeks.

Since the dispersion of the gas over the Allies lines depended entirely on the wind, it seems strange that the Germans would have employed the gas stratagem at all. They knew full well that the prevailing wind was from the West - thus favouring the Allies far a considerable part of the year. Certainly, the German's illusion that the use of toxic gas would provide quick knockout blow was quickly dispelled.

The British public was outraged by the Germans' illegal use of the toxic gas: the Hague Declaration of 1899, of which Germany was a signatory, had outlawed the 'diffusion of asphyxiating or deleterious gases'. They and the Press vociferously urged the politicians and the military of the need for retaliation. Accordingly, in May 1915, the British began a remarkable campaign to launch, from scratch, an effective response. A corps of men, initially called the Special Services Party, was quickly gathered together, under the leadership of Major Charles Foulkes, of the Royal Engineers. Foulkes was an erstwhile civil engineer with no qualifications whatsoever in the production and dispersal of toxic gas. Not withstanding this considerable drawback, Foulkes was appointed 'Gas Adviser' and given virtual carte blanche to find a rapid means of retaliation.

Comprised of civilian and enlisted science graduates, chemical specialists, and serving volunteers, the elite gas unit was quickly trained and moved to France. There, the now newly named four Special Companies, collectively over 1,400 strong (57 officers and 1,347 other ranks), began to organise an overwhelming retaliatory strike. It was scheduled to take place on the 25th September 1915, as part of the Battle of Loos. (The French just pre-empted the British with a gas attack in Champagne).

The Special Companies used basically the same chlorine gas technology as the Germans had. A total of 5,500 steel gas cylinders, containing 150 tons of chlorine gas, were used to launch the attack. It had mixed results: 2,600 British soldiers were also affected, including some of the Special Companies' own men, and seven were killed. But it was claimed that the toxic gas had facilitated the territorial gains of up to three miles that were made where the gas did penetrate the German lines. German casualties due to the chlorine gas were around 20,000 with an estimated 600 killed.

Thus, the die was cast for what most Great War soldiers considered as the most beastly element of the war. Overall, gas fatalities were relatively few, but the toxic gas caused enormous numbers of non-fatal casualties that caused intense suffering and disability; these effects often proved to be life-long to a greater or lesser extent.

Life in the trenches became dominated by the need for a perpetual alertness for gas attacks. And the ringing of the 'gas gong' - usually a empty brass shell casing - or the sounding of a 'gas horn', became a daily feature of trench life. The sheer discomfort of wearing protective helmets, clothing, and the later box respirator, for long periods was almost unendurable. Even the army horses had to be fitted with an appropriate respirator. Waging war became even more personally stressful and distressing for all concerned, perhaps even more so for the uncomprehending panic-stricken but sentient animals of burden.

In 1916, the British renamed the four existing gas companies as the 'Special Brigade' and attached to them the complement of a mortar battalion. These mortar men were required to deploy the new method of gas delivery, the gas mortar shell. (The French introduced another toxic gas, phosgene, delivered by artillery shells, at Verdun).This invention - called the Stokes mortar - used the propellant cartridge of a 4-inch mortar shell to project a steel sphere containing liquefied gas into the enemy lines. With this added facility, a whole range of toxic gases could be used to drench the enemy's trenches and dugouts. There the toxic gas could persist for hours or even days.

The early British gas shells were called T-shells and contained tear gas. K-shells holding diphosgene followed. Disphosgene, was a highly volatile gas with a rapid, if short, action and was highly toxic. 'Cocktail' gas shells were also used where combinations of the two gases, with or without an additional sneezing gas, could be simultaneously deployed.

Further cranking up the horror, in July1917 the Germans introduced Mustard Gas - or Mustard Oil - in shells that carried the highly lethal liquefied gas. The gas had a mustard- like smell. It also had a caustic effect on the skin and mucous membranes such as the eyes, nose, mouth and lungs. A huge number of casualties, many very serious, were caused by this agent. Although, again, fatalities were relatively in number few - less than 5%.

This final initiative of the British was not really a gas shell at all. In July 1917, the Special Brigade using their new Livens projectors (mortars) shelled the German lines with mortar bombs containing Thermite. This was a highly combustible mixture of iron oxide and powdered aluminium that on detonation produced a shower of flaming gas and molten metal. The Livens projector was also an effective deployer of gas shells and was widely used in closely grouped batteries to saturate an area with toxic gas.

However, perhaps the most ambitious effort at disbursing toxic gas was the British Gas Brigades 'beam attacks'. Whole trains of railway wagons filled with steel gas cylinders were drawn up parallel to the German Front Lines and the gas discharged when the wind direction was favourable. Ten such operations are recorded, dispersing 27,000 cylinders of toxic gas (equivalent to 750 tons).


In late Autumn 1914, the frantic war of movement on the Western Front came to a stuttering halt and became static trench warfare. Here, the proximity of the combattant's trenches - often measured in mere yards - made it imperative that every measure be employed to conceal the movements and disposition of the troops once they left the trenches. One of the measures employed was one of the former inconveniences of the battlefield - smoke. This deliberate production of smoke became known as making 'a smoke screen' or producing 'screening smoke'.

The most efficacious smoke screen for military purposes was found to be a visible aerosol, i.e. very small solid or liquid particles (around one micrometre in diameter) suspended in the air. These particles were found to be best produced by the incomplete combustion of selected chemicals. The particles scattered the light in all directions and produced a pronounced glare making a visually impenetrable white cloud effect. Any objects located in, or behind, the smoke screen become totally invisible to the observer.

Accordingly, the smoke screen could be used to screen objects, or landscapes, from the enemy's view. Alternatively it could be used in a deception to make the enemy's think that something was hidden and forcing them to make irrational tactical decisions.

The vagaries of the wind often made the control and persistence of a smoke screen problematic, even over a short period, and there was usually a constant need for its renewal as the smoke was dispersed.

The early use of static 'smoke-pots' and hand held 'smoke-candles' was bedevilled by these factors as well as provided only a limited zone of dispersion.

The introduction of the Stokes' mortar to the Western Front in 1915 meant suitable smoke dispensers could be propelled over long distances. And a constant and accurate replenishment rain of projectiles could be used to maintain a relatively distant smoke-screen for a considerable period. The 3-inch Stokes mortar proved to be particularly useful in this role as it could be fired up to 30 times a minute with a maximum range of 500 yards.

Smoke hand grenades, using white phosphorous to provide dense localised smoke, were not introduced until 1916. The white smoke they produced was very thick and persistent: it adsorbed water readily from the air, vastly increasing its effective volume. However, the maximum range of a thrown hand grenade was only around 25 yards, and the amount of smoke produced was quite small and localised.

The range of these smoke grenades was enhanced to up to 100 yards by using a standard infantryman's rifle. A metal rod was attached to the grenade and inserted into the 0.303-inch rifle barrel. The rod and grenade were propelled from the rifle by a blank cartridge: the British Marten Hale being the best known example of British rifle grenade launcher. Later, a similar device used a cup discharger attached to the base of the grenade to mate with the rifle: the British 'Mills' and the French 'VB' models being the most widely used by the Allies. These grenades were activated by a standard 0.303-inch rifle round, thus avoiding the need to carry the otherwise useless blank rounds. Effective close-range smoke screens could be obtained using these smoke-producing grenades.

Similar rodded and cup discharger rifle grenades that produced a range of coloured smoke were used as a means of signalling using a predetermined code. There were types of smoke-grenades for use in the day and at night.


For centuries the British Army has used flares carried in projectiles to send signals and to illuminate the battlefield. The flare carrying devices ranged from hollow cannon balls, to rockets and shells. Some of the flare(s) then descended to the ground supported by a parachute that extended the 'life' of the flare

Early in the war, a form of signalling device invented by an American naval officer Samuel W. Very (1847-1910) - the Very Light or Pistol - was introduced by the British on the Western Front. The light, or flare, was fired into the air - up to 1000 feet (305m) - from a cartridge activated by a specially designed hand-held gun. The light so produced could be white, or coloured, and persisted for 40 seconds. As such it could be used to illuminate the enemy's positions at night or, during the day or night, as a signal. By prearrangement a series of colours could be produced and a coded message broadcast across the battlefield. It is said that the signal flares could be seen for up to 28 miles on a clear night.

On occasion, in extremis, the Very Pistol was serendipitously used as a short-range anti-personnel weapon, with deadly effect.

As the war progressed, ever more sophisticted versions of the flare, or 'star-shells' were fired aloft in shells or rockets. These would explode at a predetermined height (upto 1000 feet -305 metres) releasing the flare suspended from a parachute. During its descent the flare brightly illuminated the battlefield exposing any troops that were moving around or not well concealed.

The top of the range star-shell was fired by a 18 pounder Quick-firing Gun. With various modifications and improvements new versions of these shells - designated Mark I to Mark V - were introduced during the war.

The Mark I round consisted of a brass cartridge case with a percussion primer cap and a propellant charge of eight ounces of cordite. The 'stars' (10) were packed in a paper cylinder divided into two compartments (five stars in each) by a iron disc supported on a wooden frame-work, all located into a steel casing. A bursting charge was situated on top of the 'star' case. A rotary timer was incorporated in the outer casing so the star-shell could be calibrated to operate at a specific height as determined by the operational requirements

On a much larger scale, huge carbon arc lights mounted on metal parabolic mirrors, over one metre in diameter, were used to create huge beams of parallel light. These mobile 'search-lights' were invented by Col. Alphonse Mangin of the French Army in 1877 to provide illumination on the battlefield. But on the Western Front these searchlights were found to be vulnerable to artillery and small-arms fire, and were usually kept well behind the lines and generally restricted to anti-aircraft and anti-balloon duties. Smaller units, some hand-held, were used in the trenches by all the belligerants; but principally by the Germans.


Living their troglodyte existence on the war torn Western Front, both the Allies and their foe used every stratagem they could devise to extract the smallest advantage over the enemy: to gas him in his dug-out or trench; to catch him exposed out of his trenches, and to deprive him of free movement.

The landscape would be concealed in man-made smoke; night turned into day and the very air and ground itself made poisonous and caustic.

A veritable man-made version of Hell such as the minds of the most fervent believers of the Middle Ages could never have conceived in their direst nightmares.
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