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Poison gas in World War I

2007 Schools Wikipedia Selection. Related subjects: Military History and War

   A poison gas attack using gas cylinders in World War I.
   Enlarge
   A poison gas attack using gas cylinders in World War I.

   The use of poison gas in World War I was a major military innovation.
   The gases used ranged from disabling chemicals such as tear gas and the
   more severe, mustard gas to killing agents like phosgene. This chemical
   warfare was a major component of the first global war and first total
   war of the 20th century. The killing capacity of gas was limited — only
   3% of combat deaths were due to gas — however, the proportion of
   non-fatal casualties was high and gas remained one of the soldiers'
   greatest fears. In that it was possible to develop effective
   countermeasures to gas, it was unlike most other weapons of the period.
   Hence in the later stages of the war as the use of gas increased, in
   many cases its effectiveness was diminished. This widespread use of
   these agents of chemical warfare, and wartime advances in the
   composition of high explosives, gave rise to an occasionally expressed
   view of World War I as "the chemists' war".

History

1914, tear gas

   The early uses of chemicals as weapons were as a tear inducing irritant
   ( lachrymatory), rather than fatal or disabling poisons. Although many
   believe that gases were first used in World War I, there are accounts
   that sulfur gas was used in the 5th century BC by the Spartans. During
   the first World War, the French were the first to employ gas, using
   grenades filled with tear gas ( xylyl bromide) in August 1914. Germany
   retaliated in kind in October 1914, firing fragmentation shells filled
   with a chemical irritant against French positions at Neuve Chapelle
   though the concentration achieved was so small it was barely noticed.

1915, large scale use and lethal gases

   Germany was the first to make large scale use of gas as a weapon. On 31
   January 1915, 18,000 artillery shells containing liquid xylyl bromide
   tear gas (known as T-Stoff) were fired on Russian positions on the
   Rawka River, west of Warsaw during the Battle of Bolimov. Instead of
   vaporizing, the chemical froze, completely failing to have an impact.

   Chlorine became the first killing agent to be employed. German chemical
   conglomerate IG Farben had been producing chlorine as a by-product of
   their dye manufacturing. In cooperation with Fritz Haber of the Kaiser
   Wilhelm Institute for Chemistry in Berlin, they began developing
   methods of discharging chlorine gas against enemy trenches. By 22 April
   1915, the German Army had 160 tons of chlorine deployed in 5,730
   cylinders opposite Langemarck, north of Ypres. At 17:00, in a slight
   easterly breeze, the gas was released, forming a grey-green cloud that
   drifted across positions held by French Colonial troops who broke,
   abandoning their trenches and creating an 8,000 yard (7 km) gap in the
   Allied line. However, the German infantry were also wary of the gas and
   lacked reinforcements and therefore failed to exploit the break before
   Canadian and British reinforcements arrived.

   In what became the Second Battle of Ypres, the Germans used gas on
   three more occasions; on 24 April against the Canadian 1st Division, on
   2 May near Mouse Trap Farm and on 5 May against the British at Hill 60.
   At this stage, defences against gas were non-existent; the British
   Official History stated that at Hill 60:

          "90 men died from gas poisoning in the trenches; of the 207
          brought to the nearest dressing stations, 46 died almost
          immediately and 12 after long suffering."

   Chlorine was inefficient as a weapon. It produced a visible greenish
   cloud and strong odour, making it easy to detect. It was water-soluble
   so the simple expedient of covering the mouth and nose with a damp
   cloth was effective at reducing the impact of the gas. It was thought
   to be even more effective to use urine rather than water as the ammonia
   would neutralize the chlorine, but it is now known that ammonia and
   chlorine can produce hazardously toxic fumes. Chlorine required a
   concentration of 1,000 parts per million to be fatal, destroying tissue
   in the lungs. Despite its limitations, chlorine was an effective terror
   weapon, and the sight of an oncoming cloud of the gas was a continual
   source of dread for the infantry.

British gas attacks

   The British expressed outrage at Germany's use of poison gas at Ypres
   but responded by developing their own gas warfare capability. The
   commander of British II Corps, Lt.Gen. Ferguson said of gas:
   British infantry advancing through gas at Loos, 25 September 1915.
   Enlarge
   British infantry advancing through gas at Loos, 25 September 1915.

          "It is a cowardly form of warfare which does not commend itself
          to me or other English soldiers. We cannot win this war unless
          we kill or incapacitate more of our enemies than they do of us,
          and if this can only be done by our copying the enemy in his
          choice of weapons, we must not refuse to do so."

   In the end, the British Army embraced gas with enthusiasm and mounted
   more gas attacks than any other combatant. This was due partly to the
   British spending most of the latter years of the war on the offensive.
   Also the prevailing wind on the Western Front was from the west which
   meant the British more frequently had favourable conditions for a gas
   release than the Germans. The first use of gas by the British was at
   the Battle of Loos, 25 September 1915 but the attempt was a disaster.
   Chlorine, codenamed Red Star, was the agent to be used (150 tons
   arrayed in 5,500 cylinders), and the attack was dependent on a
   favourable wind. However, on this occasion the wind proved fickle, and
   the gas either lingered in no man's land or, in places, blew back on
   the British trenches.

1915, more deadly gases

   The deficiencies of chlorine were overcome with the introduction of
   phosgene, first used by France under the direction of French chemist
   Victor Grignard in 1915. Colourless and having an odour likened to
   "mouldy hay," phosgene was difficult to detect, making it a more
   effective weapon. Later, the Germans, under the direction of German
   chemist Fritz Haber added small quantities to chlorine to increase the
   latter's toxicity. Although phosgene was sometimes used on its own, it
   was more often used mixed with an equal volume of chlorine, the
   chlorine helping to spread the denser phosgene. The Allies called this
   combination White Star after the marking painted on shells containing
   the mixture).

   Phosgene was a potent killing agent, deadlier than chlorine. It had a
   potential drawback in that the symptoms of exposure took 24 hours or
   more to manifest, meaning that the victims were initially still capable
   of putting up a fight; although this could also mean that apparently
   fit troops would be incapacitated by the effects of the gas the
   following day.

   In the first combined chlorine/phosgene attack by Germany, against
   British troops at Nieltje near Ypres, Belgium on 19 December 1915, 88
   tons of the gas were released from cylinders causing 1069 casualties
   and 69 deaths. The British P gas helmet, issued at the time, was
   impregnated with phenate hexamine and partially effective against
   phosgene. The modified PH Gas Helmet, which was additionally
   impregnated with hexamethylenetetramine to improve the protection
   against phosgene, was issued in January 1916.

   Around 36,600 tons of the gas were manufactured during the war, out of
   a total of 190,000 tons for all chemical weapons, making it second only
   to chlorine (93,800 tons) in the quantity manufactured:
     * Germany 18,100 tons
     * France 15,700 tons
     * Great Britain 1,400 tons (although they also used French stocks)
     * United States 1,400 tons (although they also used French stocks)

   Although it was never as notorious in public consciousness as mustard
   gas, it killed far more people, being responsible for about 85% of the
   100,000 deaths caused by chemical weapons during World War I.

                          CAPTION: Estimated production of gases (by type)

                             Nation              Production (metric tons)
                                    Irritant Lachrymatory Vesicant   Total
                    Austria-Hungary    5,080          255        —   5,335
                            Britain   23,870        1,010      520  25,400
                             France   34,540          810    2,040  37,390
                            Germany   55,880        3,050   10,160  69,090
                              Italy    4,070          205        —   4,275
                             Russia    3,550          155        —   3,705
                                USA    5,590            5      175   5,770
                              Total  132,580        5,490   12,895 150,965

1917, Mustard Gas

   The most widely reported and perhaps, the most effective gas of the
   First World War was mustard gas, a vesicant, which was introduced by
   Germany in July 1917 prior to the Third Battle of Ypres. Known to the
   British as HS (Hun Stuff) and Yellow Cross, mustard gas was not
   intended as a killing agent (though in high enough doses it was fatal)
   but instead was used to harass and disable the enemy and pollute the
   battlefield. Delivered in artillery shells, mustard gas was heavier
   than air, settled to the ground as an oily sherry-looking liquid and
   evaporated slowly without sunlight.
   A soldier with mustard gas burns, ca. 1914-1918.
   Enlarge
   A soldier with mustard gas burns, ca. 1914-1918.

   The polluting nature of mustard gas meant that it was not always
   suitable for supporting an attack as the assaulting infantry would be
   exposed to the gas when they advanced. When Germany launched Operation
   Michael on 21 March 1918, they saturated the Flesquières salient with
   mustard gas instead of attacking it directly, believing that the
   harassing effect of the gas, coupled with threats to the salient's
   flanks, would make the British position untenable.

   Gas never reproduced the dramatic success of 22 April 1915; however, it
   became a standard weapon which, combined with conventional artillery,
   was used to support most attacks in the later stages of the war. The
   Western Front was the main theatre in which gas was employed — the
   static, confined trench system was ideal for achieving an effective
   concentration — however, Germany made use of gas against Russia on the
   Eastern Front, where the lack of effective countermeasures would result
   in deaths of thousands of Russian infantry, while Britain experimented
   with gas in Palestine during the Second Battle of Gaza. Mustard Gas
   (Yperite) was first used by the German Army in September 1917. The most
   lethal of all the poisonous chemicals used during the war, it was
   almost odourless and took twelve hours to take effect. Yperite was so
   powerful that only small amounts had to be added to high explosive
   shells to be effective. Once in the soil, mustard gas remained active
   for several weeks.

   The skin of victims of mustard gas blistered, the eyes became very sore
   and they began to vomit. Mustard gas caused internal and external
   bleeding and attacked the bronchial tubes, stripping off the mucous
   membrane. This was extremely painful and most soldiers had to be
   strapped to their beds. It usually took a person four or five weeks to
   die of mustard gas poisoning. One nurse, Vera Brittain, wrote: "I wish
   those people who talk about going on with this war whatever it costs
   could see the soldiers suffering from mustard gas poisoning. Great
   mustard-coloured blisters, blind eyes, all sticky and stuck together,
   always fighting for breath, with voices a mere whisper, saying that
   their throats are closing and they know they will choke."

Post-war

   By the end of the war, chemical weapons had lost much of their
   effectiveness against well trained and equipped troops. At that time,
   one quarter of artillery shells fired contained chemical weapons but
   caused only 3% of the casualties.

   Nevertheless in the following years chemical weapons were used in
   several, mainly colonial, wars where one side had an advantage in
   equipment over the other. The British used adamsite against Russian
   revolutionary troops in 1919 and mustard against Iraqi insurgents in
   the 1920s; Spain used chemical weapons in Morocco against Rif tribesmen
   throughout the 1920s and Italy used mustard gas in Libya in 1930 and
   again during its invasion of Ethiopia in 1936 . In 1925, a Chinese
   warlord, Zhang Zuolin, contracted a German company to build him a
   mustard gas plant in Shengyang , which was completed in 1927.

   Public opinion had by then turned against the use of such weapons,
   which led to the Geneva Protocol, a treaty banning the use (but not the
   stockpiling) of lethal gas and bacteriological weapons which was signed
   by most First World War combatants in 1925. Most countries that signed
   ratified it within around five years, although a few took much longer
   Brazil, Japan, Uruguay and the United States did not do so until the
   1970s and Nicaragua ratified it only in 1990 .

   Although all major combatants stockpiled chemical weapons during the
   Second World War, the only reports of its use in the conflict were the
   Japanese use of relatively small amounts of mustard gas and lewisite in
   China , and very rare occurrences in Europe (for example some sulfur
   mustard bombs were dropped on Warsaw on 3 September 1939, which Germany
   acknowledged in 1942 but indicated that it had been accidental ).
   Mustard gas was the agent of choice, with the British stockpiling
   40,719 tons, the Russians 77,400 tons, the Americans over 87,000 tons
   and the Germans 27,597 tons .

   The mustard gas with which the British hoped to repel an invasion of
   the United Kingdom in 1940 was never needed , and a fear that the
   allies also had nerve agents prevented their deployment by Germany.
   Nevertheless poison gas technology played an important role in the
   Holocaust.

   Although chemical weapons have been used in at least a dozen wars since
   the end of the First World War , they have never been used again in
   combat on such a large scale. Nevertheless, the use of mustard gas and
   the more deadly nerve agents by Iraq during the 8-year Iran-Iraq war
   killed around 20,000 Iranian troops (and injured another 80,000),
   around a quarter of the number of deaths caused by chemical weapons
   during the First World War .

Casualties

   British 55th (West Lancashire) Division troops blinded by tear gas
   during the Battle of Estaires, 10 April 1918.
   Enlarge
   British 55th (West Lancashire) Division troops blinded by tear gas
   during the Battle of Estaires, 10 April 1918.

   The contribution of gas weapons to the total casualty figures was
   relatively minor. British figures, which were accurately maintained
   from 1916, recorded that only 3% of gas casualties were fatal, 2% were
   permanently invalid and 70% were fit for duty again within six weeks.
   All gas casualties were mentally scarred by exposure, and gas remained
   one of the great fears of the front-line soldier.

          "It was remarked as a joke that if someone yelled 'Gas',
          everyone in France would put on a mask. ... Gas shock was as
          frequent as shell shock." (H. Allen, Towards the Flame, 1934)

          Gas! GAS! Quick, boys! - An ecstasy of fumbling,
          Fitting the clumsy helmets just in time;
          But someone still was yelling out and stumbling,
          And flound'ring like a man in fire or lime...
          Dim, through the misty panes and thick green light,
          As under a green sea, I saw him drowning.
          In all my dreams, before my helpless sight,
          He plunges at me, guttering, choking, drowning.

          ( Wilfred Owen, " Dulce Et Decorum Est", 1917)

   Death by gas was particularly horrific. According to Denis Winter
   (Death's Men, 1978), a fatal dose of phosgene eventually led to
   "shallow breathing and retching, pulse up to 120, an ashen face and the
   discharge of four pints (2 litres) of yellow liquid from the lungs each
   hour for the 48 of the drowning spasms."

   A common fate of those exposed to gas was blindness, tear gas or
   mustard gas being the main causes. It became a frequent spectacle to
   see lines of blinded soldiers, hand on the shoulder of the man in
   front, being guided by a sighted man to a dressing station. One of the
   most famous First World War paintings, Gassed by John Singer Sargent,
   captures such a scene of mustard gas casualties which he witnessed at a
   dressing station at Le Bac-du-Sud near Arras in July 1918.
   Nation          Gas casualties (estimated)
                   Fatal  Non-fatal
   Russia          50,000              400,000
   Germany         10,000              190,000
   France           8,000              182,000
   Britain          8,000              181,000
   Austria-Hungary  3,000               97,000
   USA              1,500               71,500
   Italy            4,500               55,000
   Total           85,000            1,176,500

   Mustard gas caused the most gas casualties on the Western Front,
   despite being produced in smaller quantities than irritant gases such
   as chlorine and phosgene. The proportion of mustard gas fatalities to
   total casualties was low; only 2% of mustard gas casualties died and
   many of these succumbed to secondary infections rather than the gas
   itself. Once it was introduced at Ypres, mustard gas produced 90% of
   all British gas casualties and 14% of battle casualties of any type.

   Mustard gas was a source of extreme dread. In The Anatomy of Courage
   (1945), Lord Moran, who had been a medical officer during the war,
   wrote: "After July 1917 gas partly usurped the role of high explosive
   in bringing to head a natural unfitness for war. The gassed men were an
   expression of trench fatigue, a menace when the manhood of the nation
   had been picked over."

   Mustard gas did not need to be inhaled to be effective — any contact
   with skin was sufficient. Exposure to 0.1 ppm was enough to cause
   massive blisters. Higher concentrations could burn flesh to the bone.
   It was particularly effective against the soft skin of the face and
   genitals. Typical exposure would result in swelling of the conjunctiva
   and eyelids, forcing them closed and rendering the victim temporarily
   blind. Where it contacted the skin, moist red patches would immediately
   appear which after 24 hours would have formed into blisters. Other
   symptoms included severe headache, elevated pulse and temperature, and
   pneumonia.

   Death by mustard gas, when it came, was dreadful. A post-mortem account
   from the British official medical history records one of the first
   British casualties:

          Case four. Aged 39 years. Gassed 29 July 1917. Admitted to
          casualty clearing station the same day. Died about ten days
          later. Brownish pigmentation present over large surfaces of the
          body. A white ring of skin where the wrist watch was. Marked
          superficial burning of the face and scrotum. The larynx much
          congested. The whole of the trachea was covered by a yellow
          membrane. The bronchi contained abundant gas. The lungs fairly
          voluminous. The right lung showing extensive collapse at the
          base. Liver congested and fatty. Stomach showed numerous
          submucous haemorrhages. The brain substance was unduly wet and
          very congested.

   A British nurse treating mustard gas cases recorded:

          "They cannot be bandaged or touched. We cover them with a tent
          of propped-up sheets. Gas burns must be agonizing because
          usually the other cases do not complain even with the worst
          wounds but gas cases are invariably beyond endurance and they
          cannot help crying out."

   CAPTION: British gas casualties on the Western Front

   Date                        Agent       Casualties (official)
                                           Fatal Non-fatal
   April – May 1915            Chlorine      350           7,000
   May 1915 – June 1916        Lachrymants     0               0
   December 1915 – August 1916 Chlorine    1,013           4,207
   July 1916 – July 1917       Various       532           8,806
   July 1917 – November 1918   Mustard gas 4,086         160,526
   April 1915 – November 1918  Total       5,981         180,539

   Many of those who survived a gas attack were scarred for life.
   Respiratory disease and failing eye sight were common post-war
   afflictions. Of the Canadians who, without any effective protection,
   had withstood the first chlorine attacks during 2nd Ypres, 60% of the
   casualties had to be repatriated and half of these were still unfit by
   the end of the war, over three years later.

   In reading the statistics of the time, one should bear the longer term
   in mind. Many of those who were fairly soon recorded as fit for service
   were left with scar tissue in their lungs. This tissue was susceptible
   to tuberculosis attack. It was from this that many of the 1918
   casualties died, around the time of the Second World War, shortly
   before the sulfa drugs became widely available for its treatment.

Countermeasures

   None of the First World War combatants were prepared for the
   introduction of poison gas as a weapon. Once gas had appeared,
   development of gas protection began and the process continued for much
   of the war producing a series of increasingly effective gas masks.

   Even at 2nd Ypres Germany, still unsure of the weapon's effectiveness,
   only issued breathing masks to the engineers handling the gas. At Ypres
   a Canadian medical officer, who was also a chemist, quickly identified
   the gas as chlorine and recommended that the troops urinate on a cloth
   and hold it over their mouth and nose, the theory being the uric acid
   would crystallise the chlorine. The first official equipment issued was
   similarly crude; a pad of material, usually impregnated with a
   chemical, tied over the lower face. To protect the eyes from tear gas,
   soldiers were issued with gas goggles.
   British Vickers machine gun crew wearing PH gas helmets with exhaust
   tubes.
   Enlarge
   British Vickers machine gun crew wearing PH gas helmets with exhaust
   tubes.

   The next advance was the introduction of the gas helmet — basically a
   bag placed over the head. The fabric of the bag was impregnated with a
   chemical to neutralise the gas — whenever it rained, the chemical would
   wash out into the soldier's eyes. Eye-pieces, which were prone to fog
   up, were initially made from talc. When going into combat, gas helmets
   were typically worn rolled up on top of the head, to be pulled down and
   secured about the neck when the gas alarm was given. The first British
   version was the Hypo helmet, the fabric of which was soaked in sodium
   hyposulfite (commonly known as "hypo"). The British P gas helmet,
   partially effective against phosgene and with which all infantry were
   equipped with at Loos, was impregnated with phenate hexamine. A
   mouthpiece was added through which the wearer would breathe out to
   prevent carbon dioxide build-up. The adjutant of the 1/23rd Battalion,
   The London Regiment, recalled his experience of the P helmet at Loos:

          "The goggles rapidly dimmed over, and the air came through in
          such suffocatingly small quantities as to demand a continuous
          exercise of will-power on the part of the wearers."

   A modified version of the P Helmet, called the PH Helmet, was issued in
   January 1916, and was additionally impregnated with
   hexamethylenetetramine to improve the protection against phosgene .
   Australian infantry wearing Small Box Respirators, Ypres, September
   1917.
   Enlarge
   Australian infantry wearing Small Box Respirators, Ypres, September
   1917.

   Self-contained box respirators represented the culmination of gas mask
   development during the First World War. Box respirators used a
   two-piece design; a mouthpiece connected via a hose to a box filter.
   The box filter contained granules of chemicals that neutralised the
   gas, delivering clean air to the wearer. Separating the filter from the
   mask enabled a bulky but efficient filter to be supplied. Nevertheless,
   the first version, known as the Large Box Respirator (LBR) or
   "Harrison's Tower", was deemed too bulky — the "box" canister needed to
   be carried on the back. The LBR had no mask, just a mouthpiece and nose
   clip; separate gas goggles had to be worn. It continued to be issued to
   the artillery gun crews but the infantry were supplied with the "Small
   Box Respirator" (SBR).

   The Small Box Respirator featured a single-piece, close-fitting
   rubberised mask with eye-pieces. The box filter was compact and could
   be worn around the neck. The SBR could be readily upgraded as more
   effective filter technology was developed. The British-designed SBR was
   also adopted for use by the American Expeditionary Force. The SBR was
   the prized possession of the ordinary infantryman; when the British
   were forced to retreat during the German Spring Offensive of 1918, it
   was found that while some troops had discarded their rifles, hardly any
   had left behind their respirators.

   It was not only humans that needed protection from gas; horses and
   mules, which were the main means of transport, were also vulnerable to
   gas and needed to be provided with protection. As animals were never
   used near the front-line, protection from gas only became necessary
   when the practice of firing gas shells into rear areas was adopted.

   For mustard gas, which did not need to be inhaled in order to inflict
   casualties, no effective countermeasure was found during the war. The
   kilt-wearing Highland regiments of Scotland were especially vulnerable
   to mustard gas injuries due to their bare legs. At Nieuport some Scots
   battalions took to wearing women's tights beneath the kilt as a form of
   protection.

   The Canadian soldiers are said to have found a way to minimize the
   effects of the mustard gas. Since the gas was sent by the wind towards
   them, they understood that it would minimize the exposure to the gas if
   the Canadians not only did not flee but ran through the gas. The
   French, conversely, when the gas was used against them, fled, and
   therefore spent more time in the gas, suffering greater casualties.
   Gas alert by Arthur Streeton, 1918.
   Enlarge
   Gas alert by Arthur Streeton, 1918.

   Gas alert procedure became a routine for the front-line soldier. To
   warn of a gas attack, a bell would be rung, often made from a spent
   artillery shell. At the noisy batteries of the siege guns, a compressed
   air strombus horn was used, which could be heard nine miles away.
   Notices would be posted on all approaches to an affected area, warning
   people to take precautions.

   Other British attempts at countermeasures were not so effective. An
   early plan was to use 100,000 fans to disperse the gas. Burning coal or
   carborundum dust was tried. A proposal was made to equip front-line
   sentries with diving helmets, air being pumped to them through a 100 ft
   (30 m) hose.

   However, the effectiveness of all countermeasures is apparent. In 1915,
   when poison gas was relatively new, less than 3% of British gas
   casualties died. In 1916, the proportion of fatalities jumped to 17%.
   By 1918, the figure was back below 3%, though the total number of
   British gas casualties was now nine times the 1915 levels.

   Various gas masks employed on the Western Front during the war.
   Enlarge
   Various gas masks employed on the Western Front during the war.

Delivery systems

   A British cylinder release at Montauban on the Somme, June 1916 — part
   of the preparation for the Battle of the Somme.
   Enlarge
   A British cylinder release at Montauban on the Somme, June 1916 — part
   of the preparation for the Battle of the Somme.

   The first system employed for the mass delivery of gas involved
   releasing the gas from cylinders in a favourable wind such that it was
   carried over the enemy's trenches. The main advantage of this method
   was that it was relatively simple and, in suitable atmospheric
   conditions, produced a concentrated cloud capable of overwhelming the
   gas mask defences. The disadvantages of cylinder releases were
   numerous. First and foremost, delivery was at the mercy of the wind. If
   the wind was fickle, as was the case at Loos, the gas could backfire,
   causing friendly casualties. Gas clouds gave plenty of warning,
   allowing the enemy time to protect themselves, though many soldiers
   found the sight of a creeping gas cloud unnerving. Also gas clouds had
   limited penetration, only capable of affecting the front-line trenches
   before dissipating.

   Finally, the cylinders had to be emplaced at the very front of the
   trench system so that the gas was released directly over no man's land.
   This meant that the cylinders had to be manhandled through
   communication trenches, often clogged and sodden, and stored at the
   front where there was always the risk that cylinders would be
   prematurely breached during a bombardment. A leaking cylinder could
   issue a telltale wisp of gas that, if spotted, would be sure to attract
   shellfire.
   German gas attack on the eastern front.
   Enlarge
   German gas attack on the eastern front.

   A British chlorine cylinder, known as an "oojah", weighed 190 lb (86
   kg), of which only 60 lb (27 kg) was chlorine gas, and required two men
   to carry. Phosgene gas was introduced later in a cylinder, known as a
   "mouse", that only weighed 50 lb (23 kg).

   Delivering gas via artillery shell overcame many of the risks of
   dealing with gas in cylinders. The Germans, for example, used 5.9 inch
   artillery shells. Gas shells were independent of the wind and increased
   the effective range of gas, making anywhere within reach of the guns
   vulnerable. Gas shells could be delivered without warning, especially
   the clear, nearly odourless phosgene — there are numerous accounts of
   gas shells, landing with a "plop" rather than exploding, being
   initially dismissed as dud HE or shrapnel shells, giving the gas time
   to work before the soldiers were alerted and took precautions.
   Loading a battery of Livens gas projectors.
   Enlarge
   Loading a battery of Livens gas projectors.

   The main flaw associated with delivering gas via artillery was the
   difficulty of achieving a killing concentration. Each shell had a small
   gas payload and an area would have to be subjected to a saturation
   bombardment to produce a cloud to match cylinder delivery. Mustard gas,
   however, did not need to form a concentrated cloud and hence artillery
   was the ideal vehicle for delivery of this battlefield pollutant.

   The solution to achieving a lethal concentration without releasing from
   cylinders was the "gas projector", essentially a large-bore mortar that
   fired the entire cylinder as a missile. The British Livens projector
   (invented by Captain W.H. Livens in 1917) was a simple device; an
   8-inch diameter tube sunk into the ground at an angle, a propellant was
   ignited by an electrical signal, firing the cylinder containing 30 or
   40 lb (14 or 18 kg) of gas up to 1,900 metres. By arranging a battery
   of these projectors and firing them simultaneously, a dense
   concentration of gas could be achieved. The Livens was first used at
   Arras on 4 April 1917. On 31 March 1918 the British conducted their
   largest ever "gas shoot", firing 3,728 cylinders at Lens.

Unexploded weapons

   Unexploded WWI ammunition, including chemical ammunition, was a major
   problem in former battle areas after the end of the War, and has ever
   since been present. Shells may be, for instance, uncovered when farmers
   plough their fields; more importantly, shells are regularly discovered
   when public works or construction work is done. While classical shells
   pose a risk of explosion, their disposal is relatively easy. This is
   not the case with chemical shells.

   An additional difficulty is the current stringency of environmental
   legislation. In the past, a common method of getting rid of unexploded
   chemical ammunition was to detonate or dump it at sea; this is nowadays
   prohibited in most countries.

   The problems are especially acute in some northern regions of France.
   The French government no longer disposes of chemical weapons at sea.
   For this reason, piles of untreated chemical weapons accumulated. In
   2001, it became evident that the pile stored at a depot in Vimy was
   unsafe; the inhabitants of the neighbouring town were evacuated, and
   the pile moved, using refrigerated trucks and under heavy guard, to a
   military camp in Suippes. The French government announced the
   construction of an automated plant for the dismantling of chemical
   munitions inherited from previous wars; this factory, codenamed SECOIA,
   is to be operational in 2007. The capacity of the plant is meant to be
   25 tons per year (extensible to 80 tons at the beginning), for a
   lifetime of 30 years.

   In Belgium, a similar plant was planned in 1993 and brought in service
   in 1999, two years late, indicating the difficulties in disposal of
   such wastes. Germany, too, has to deal with unexploded ammunition and
   polluted lands resulting from the explosion of an ammunition train in
   1919.

Gases used

   CAPTION: A=Allies, C=Central Powers

   Name First use Type Used by
   Chlorine 1915 Irritant/Lung Both
   Phosgene 1915 Irritant/Skin and mucous membranes, corrosive, toxic Both
   Chloromethyl chloroformate 1915 Irritant/Eyes, skin, lungs Both
   Trichloromethyl chloroformate 1916 Severe irritant, causes burns Both
   Chloropicrin 1916 Irritant, lachrymatory, toxic Both
   Stannic chloride 1916 Severe irritant, causes burns A
   a-Chlorotoluene (Benzyl chloride) 1917 Irritant, lachrymatory C
   Bis(chloromethyl) ether (Dichloromethyl ether) 1918 Irritant, can blur
   vision C
   Diphenylchloroarsine (Diphenyl chlorasine) 1917 Irritant/Sternutatory C
   Ethyldichloroarsine 1918 Vesicant C
   N-Ethylcarbazole 1918 Irritant C
   Benzyl bromide 1915 Lachrymatory C
   Xylyl bromide 1914 Lachrymatory, toxic Both
   Methyl chlorosulfonate 1915 C
   Ethyl iodoacetate 1916 Lachrymatory A
   Bromoacetone 1916 Lachrymatory, irritant Both
   Bromomethyl ethyl ketone 1916 Irritant/Skin, eyes C
   Acrolein 1916 Lachrymatory, toxic A
   Hydrocyanic acid (Prussic acid) 1916 Paralyzing A
   Hydrogen sulfide (Sulphuretted hydrogen) 1916 Irritant, toxic A
   Mustard gas (Bis(2-chloroethyl) sulfide) 1917 Vesicant (blistering
   agent) Both

Effect on World War II

   In the Geneva Gas Protocol of the Third Geneva Convention, signed in
   1925, the signatory nations agreed not to use poison gas in the future,
   stating "the use in war of asphyxiating, poisonous or other gases, and
   of all analogous liquids, materials or devices, has been justly
   condemned by the general opinion of the civilised world."

   Nevertheless, precautions were taken in World War II. In both Axis and
   Allied nations, children in school were taught to wear gas masks in
   case of gas attack. Italy did use poison gas against Ethiopia in 1935
   and 1936, and Japan used gas against China in 1941. Germany developed
   the poison gases tabun, sarin, and soman during the war, and,
   infamously, used Zyklon_B in Nazi extermination camps. Neither Germany
   nor the Allied nations used any of their war gases in combat, possibly
   heeding warnings of awful retaliation.
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   with only minor checks and changes (see www.wikipedia.org for details
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