Phosgene

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Phosgene

 

Phosgene

Names
Preferred IUPAC name Carbonyl dichloride
Other names Carbonyl chloride CG Carbon dichloride oxide Carbon oxychloride Chloroformyl chloride Dichloroformaldehyde Dichloromethanone Dichloromethanal
Identifiers
CAS Number	75-44-5
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29365
ChemSpider	6131
ECHA InfoCard	100.000.792
EC Number	200-870-3
PubChem CID	6371
RTECS number	SY5600000
UNII	117K140075
UN number	1076
CompTox Dashboard (EPA)	DTXSID0024260
InChI[show]
SMILES[show]
Properties
Chemical formula	COCl2, also CCl2O
Molar mass	98.92 g/mol
Appearance	Colorless gas
Odor	Suffocating, like musty hay
Density	4.248 g/L (15 °C, gas) 1.432 g/cm3 (0 °C, liquid)
Melting point	−118 °C (−180 °F; 155 K)
Boiling point	8.3 °C (46.9 °F; 281.4 K)
Solubility in water	Insoluble, reacts
Solubility	Soluble in benzene, toluene, acetic acid Decomposes in alcohol and acid
Vapor pressure	1.6 atm (20°C)
Magnetic susceptibility (χ)	−48·10−6 cm3/mol
Structure
Molecular shape	Planar, trigonal
Dipole moment	1.17 D
Hazards
Safety data sheet	ICSC 0007
EU classification (DSD) (outdated)	T+
R-phrases (outdated)	R26 R34
S-phrases (outdated)	(S1/2) S9 S26 S36/37/39 S45
NFPA 704 (fire diamond)	0 4 1
Flash point	Non-flammable
Threshold limit value (TLV)	0.1 ppm
Lethal dose or concentration (LD, LC):
LC50 (median concentration)	500 ppm (human, 1 min) 340 ppm (rat, 30 min) 438 ppm (mouse, 30 min) 243 ppm (rabbit, 30 min) 316 ppm (guinea pig, 30 min) 1022 ppm (dog, 20 min) 145 ppm (monkey, 1 min)
LCLo (lowest published)	3 ppm (human, 2.83 h) 30 ppm (human, 17 min) 50 ppm (mammal, 5 min) 88 ppm (human, 30 min) 46 ppm (cat, 15 min) 50 ppm (human, 5 min) 2.7 ppm (mammal, 30 min)
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.1 ppm (0.4 mg/m3)
REL (Recommended)	TWA 0.1 ppm (0.4 mg/m3) C 0.2 ppm (0.8 mg/m3) [15-minute]
IDLH (Immediate danger)	2 ppm
Related compounds
Related compounds	Thiophosgene Formaldehyde Carbonic acid Urea Carbon monoxide Chloroformic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Phosgene is the organic chemical compound with the formula COCl₂. It is a colorless gas; in low concentrations, its odor resembles that of freshly cut hay or grass. Phosgene is a valued industrial building block, especially for the production of urethanes and polycarbonate plastics.

It is very poisonous and was used as a chemical weapon during World War I, when it was responsible for 85,000 deaths.

In addition to its industrial production, small amounts occur from the breakdown and the combustion of organochlorine compounds.

Structure and basic properties

Phosgene is a planar molecule as predicted by VSEPR theory. The C=O distance is 1.18 Å, the C−Cl distance is 1.74 Å and the Cl−C−Cl angle is 111.8°. It is one of the simplest acyl chlorides, being formally derived from carbonic acid.

Production

Industrially, phosgene is produced by passing purified carbon monoxide and chlorine gas through a bed of porous activated carbon, which serves as a catalyst:

CO + Cl₂ → COCl₂ (ΔH_rxn = −107.6 kJ/mol)

The reaction is exothermic, therefore the reactor must be cooled. Typically, the reaction is conducted between 50 and 150 °C. Above 200 °C, phosgene reverts to carbon monoxide and chlorine, K_eq(300 K) = 0.05. World production of this compound was estimated to be 2.74 million tonnes in 1989.

Because of safety issues, phosgene is often produced and consumed within the same plant, and extraordinary measures are made to contain it. It is listed on Schedule 3 of the Chemical Weapons Convention: All production sites manufacturing more than 30 tonnes per year must be declared to the OPCW. Although less dangerous than many other chemical weapons such as sarin, phosgene is still regarded as a viable chemical warfare agent because it is so easy to manufacture when compared to the production requirements of more technically advanced chemical weapons such as the first-generation nerve agent tabun.

Inadvertent generation

Upon ultraviolet (UV) radiation in the presence of oxygen, chloroform slowly converts into phosgene by a radical reaction. To suppress this photodegradation, chloroform is often stored in brown-tinted glass containers and with a small percentage of ethanol added. Chlorinated solvents used to remove oil from metals, such as automotive brake cleaners, are converted to phosgene by the UV rays of arc welding processes.

Phosgene may also be produced during testing for leaks of older-style refrigerant gases.

 Chloromethanes (R12, R22 and others) were formerly leak-tested in situ by employing a small gas torch (propane, butane, or propylene gas) with a sniffer tube and a copper reaction plate in the flame nozzle of the torch. If any refrigerant gas was leaking from a pipe or joint, the gas would be sucked into the flame through the sniffer tube and would cause a colour change of the gas flame to a bright greenish blue. In the process, phosgene gas would be created due to the thermal reaction. No valid statistics are available, but anecdotal reports suggest that numerous refrigeration technicians suffered the effects of phosgene poisoning due to their ignorance of the toxicity of phosgene, produced during such leak testing.

Electronic sensing of refrigerant gases phased out the use of flame testing for leaks in the 1980s. Similarly, phosgene poisoning is a possibility for people fighting fires that occur in the vicinity of refrigerant leaks from air-conditioning systems or refrigeration equipment, smoking in the vicinity of a freon refrigerant leak, or fighting fires using halon or halotron.

Phosgene can be released during building fires. In one instance, a deputy fire chief died ten days after inhaling fumes that wafted down outside a burning restaurant. After a two-day hospitalization he had appeared to recover, but ultimately suffered cardiac arrest at home following tracheobronchial inflammation, alveolar hemorrhage, and pulmonary edema. The phosgene was produced by decomposing Freon 22 after flames ducted up from a grease fire heated an air-conditioning unit on the roof and ruptured a hose.

History

Phosgene was synthesized by the Cornish chemist John Davy (1790–1868) in 1812 by exposing a mixture of carbon monoxide and chlorine to sunlight. He named it "phosgene" in reference of the use of light to promote the reaction; from Greek, phos (light) and gene (born). It gradually became important in the chemical industry as the 19th century progressed, particularly in dye manufacturing.

Reactions and uses

The great majority of phosgene is used in the production of isocyanates, the most important being toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). These two isocyanates are precursors to polyurethanes. The reaction of an organic substrate with phosgene is called phosgenation.

Synthesis of carbonates

Significant amounts are also used in the production of polycarbonates by its reaction with bisphenol A. Polycarbonates are an important class of engineering thermoplastic found, for example, in lenses in eyeglasses. Diols react with phosgene to give either linear or cyclic carbonates (R = H, alkyl, aryl):

HOCR₂−X−CR₂OH + COCl₂ → ​¹⁄_n [OCR₂−X−CR₂OC(O)−]_n + 2 HCl

Phosgenation of hydroxamic acids gives dioxazolone, a class of cyclic carbonate esters:

RC(O)NHOH + COCl₂ → RC=NOCO₂ + 2 HCl

Synthesis of isocyanates

The synthesis of isocyanates from amines illustrates the electrophilic character of this reagent and its use in introducing the equivalent of "CO²⁺":

RNH₂ + COCl₂ → RN=C=O + 2 HCl (R = alkyl, aryl)

Such reactions are conducted in the presence of a base such as pyridine that absorbs the hydrogen chloride.

Laboratory uses

In the research laboratory phosgene still finds limited use in organic synthesis. A variety of substitutes have been developed, notably trichloromethyl chloroformate ("diphosgene"), a liquid at room temperature, and bis(trichloromethyl) carbonate ("triphosgene"), a crystalline substance. Aside from the above reactions that are widely practiced industrially, phosgene is also used to produce acyl chlorides and carbon dioxide from carboxylic acids:

RCO₂H + COCl₂ → RC(O)Cl + HCl + CO₂

Such acid chlorides react with amines and alcohols to give, respectively, amides and esters, which are commonly used intermediates. Thionyl chloride is more commonly and more safely employed for this application. A specific application for phosgene is the production of chloroformic esters:

ROH + COCl₂ → ROC(O)Cl + HCl

Phosgene is stored in metal cylinders. The outlet is always standard, a tapered thread that is known as CGA 160

Other chemistry

Although it is somewhat hydrophobic, phosgene reacts with water to release hydrogen chloride and carbon dioxide:

COCl₂ + H₂O → CO₂ + 2 HCl

Analogously, with ammonia, one obtains urea:

COCl₂ + 4 NH₃ → CO(NH₂)₂ + 2 NH₄Cl

Halide exchange with nitrogen trifluoride and aluminium tribromide gives COF₂ and COBr₂, respectively.

Chemical warfare

US Army phosgene identification poster from World War II

The collapse of international conventions against chemical weapons led to the widespread use of chlorine gas in World War I, but its lethal concentration of 0.1% was visible as a green cloud in the air, allowing troops to take readily available countermeasures. Phosgene, colorless with a more subtle "moldy hay" odor, was introduced by a group of French chemists led by Victor Grignard and first used by the French in 1915. It was also used in a mixture with an equal volume of chlorine, with the chlorine helping to spread the denser phosgene.  Phosgene was more potent than chlorine, though some of the symptoms of exposure took 24 hours or more to manifest, meaning the victims were initially still capable of putting up a fight.

Following the extensive use of phosgene gas in combat during World War I, it was stockpiled by various countries as part of their secret chemical weapons programs.

In May 1928, eleven tons of phosgene escaped from a war surplus store in central Hamburg. Three hundred people were poisoned, of whom 10 died.

Phosgene was then only infrequently used by the Imperial Japanese Army against the Chinese during the Second Sino-Japanese War. Gas weapons, such as phosgene, were produced by Unit 731 and authorized by specific orders given by Hirohito (Emperor Showa) himself, transmitted by the chief of staff of the army. For example, the Emperor authorized the use of toxic gas on 375 separate occasions during the Battle of Wuhan from August to October 1938.

Safety

Phosgene is an insidious poison as the odor may not be noticed and symptoms may be slow to appear.

The odor detection threshold for phosgene is 0.4 ppm, four times the threshold limit value. Its high toxicity arises from the action of the phosgene on the proteins in the pulmonary alveoli, the site of gas exchange: their damage disrupts the blood–air barrier, causing suffocation. It reacts with the amines of the proteins, causing crosslinking by formation of urea-like linkages, in accord with the reactions discussed above. Phosgene detection badges are worn by those at risk of exposure.

Sodium bicarbonate may be used to neutralise liquid spills of phosgene. Gaseous spills may be mitigated with ammonia.

Accidents

• On January 23, 2010, an accidental release of phosgene gas at a DuPont facility in West Virginia killed one employee.

Chemical weapons and the United Kingdom

From Wikipedia, the free encyclopedia

Chemical weapons were widely used by the United Kingdom in World War I, and while the use of tear gas was suggested by Churchill and others postwar in Mesopotamia and in World War II, it appears that they were not actually used, although some historians disagree. While the UK was a signatory of the Hague Conventions of 1899 and 1907 which outlawed the use of poison gas shells, the conventions omitted mention of deployment from cylinders, probably because that had not been considered.

The United Kingdom ratified the Geneva Protocol on 9 April 1930. The UK signed the Chemical Weapons Convention on 13 January 1993 and ratified it on 13 May 1996.

Use in World War I

A World War I-era British gas bomb

During the First World War, in retaliation to the use of chlorine by Germany against British troops from April 1915 onwards, the British Army deployed chlorine themselves for the first time during the Battle of Loos on 25 September 1915. By the end of the war, poison gas use had become widespread on both sides and by 1918 a quarter of artillery shells were filled with gas and Britain had produced around 25,400 tons of toxic chemicals.

Britain used a range of poison gases, originally chlorine and later phosgene, diphosgene and mustard gas. They also used relatively small amounts of the irritant gases chloromethyl chloroformate, chloropicrin, bromacetone and ethyl iodoacetate. Gases were frequently mixed, for example white star was the name given to a mixture of equal volumes of chlorine and phosgene, the chlorine helping to spread the denser but more toxic phosgene. Despite the technical developments, chemical weapons suffered from diminishing effectiveness as the war progressed because of the protective equipment and training which the use engendered on both sides.

Mustard gas was first used effectively in World War I by the Imperial German Army against Commonwealth soldiers in the Battle of Passchendaele near Ypres, Belgium, in 1917 and later also against the French Second Army. The name Yprite comes from its usage by the German army near the town of Ypres. The Allies did not use mustard gas until November 1917 at the Battle of Cambrai after the armies had captured a stockpile of German mustard-gas shells. It took the British more than a year to develop their own mustard gas weapon, with production of the chemicals centred on Avonmouth Docks. (The only option available to the British was the Despretz–Niemann–Guthrie process). This was used first in September 1918 during the breaking of the Hindenburg Line with the Hundred Days' Offensive.

The use of chemical weapons in warfare during the Great War was in violation of the 1899 Hague Declaration Concerning Asphyxiating Gases and the 1907 Hague Convention on Land Warfare, which explicitly forbade the use of "poison or poisoned weapons" in warfare.

Between the wars

To maintain a stockpile of Adamsite, the British Ministry of Munitions established Sutton Oak Chemical Defence Research Establishment (CDRE) in 1919. The plant was able to manufacture up to 20 tons of mustard gas per week in the late 1920s.

After the war, the Royal Air Force dropped diphenylchloroarsine, an irritant agent designed to cause uncontrollable coughing, on Bolshevik troops in 1919, and Winston Churchill, secretary of state for war and air, suggested that the RAF use tear gas in Iraq in 1920 during a major revolt there. However, historians are divided as to whether or not gas was actually used.

It is sheer affectation to lacerate a man with the poisonous fragment of a bursting shell and to boggle at making his eyes water by means of lachrymatory gas. I am strongly in favour of using poisoned gas against uncivilised tribes. The moral effect should be so good that the loss of life should be reduced to a minimum. It is not necessary to use only the most deadly gasses: gasses can be used which cause great inconvenience and would spread a lively terror and yet would leave no serious permanent effects on most of those affected.

— Winston Churchill, Departmental minute (1919)

Usage of the term "poisoned gas" by Churchill in a way suggesting he promoted lethal chemical warfare was circulated in 2000's in response to British criticism of the use of chemical weapons in the Syrian Civil War.

In 1937 ICI began to build a new factory for Mustard Gas at their Randle plant on Wigg Island, Runcorn, Cheshire.

Britain signed and ratified the Geneva Protocol in 1930, which banned the use of toxic gases and bacteria in war but not the development and production of such weapons. Britain carried out extensive testing of chemical weapons from the early 1930s onwards. In the Rawalpindi experiments, hundreds of Indian soldiers were exposed to mustard gas in an attempt to determine the appropriate dosage to use on battlefields. Many of the subjects suffered severe burns from their exposure to the gas.

Proposed use in World War II

In the late 1930s the Chamberlain Government planned that the United Kingdom should be in a position at the beginning of any war to retaliate in kind if the Germans, as expected, used mustard gas and phosgene. to help repel a German invasion in 1940–1941, and had there been an invasion may have also deployed it against German cities. General Brooke, in command of British anti-invasion preparations of World War II said that he "...had every intention of using sprayed mustard gas on the beaches" in an annotation in his diary. The British manufactured mustard, chlorine, lewisite, phosgene and Paris Green and stored it at airfields and depots for use on the beaches.

M. S. Factory, Valley

In the late 1930s the Chamberlain Government planned that the United Kingdom should be in a position at the beginning of any war to retaliate in kind if the Germans, as expected, used mustard gas. In April/June 1939 the Alyn Valley in Rhydymwyn was surveyed by the Department of Industrial Planning on behalf of the Ministry of Supply and Imperial Chemical Industries (ICI) who were tasked with managing this programme. This resulted in M. S. Factory, Valley as United Kingdoms main chemical weapons plant.

Forward Filling Depots

To able to retaliate quickly if Nazi Germany used chemical weapons, a number of Forward Filling Depots were built so that the mustard gas stockpile was dispersed and ready to use.

• FFD 1 RAF Barnham, Heath Site. Under the control of 94 Maintenance Unit
• FFD 2 RAF RiselyLake Site. American FFD - Station 572
• FFD 3 RAF Station Swinderby Under the control of 93 Maintenance Unit
• FFD 4 Bridge Site. Under the control of 95 Maintenance Unit
• FFD 5 Station Site. Under the control of 80 Sub Maintenance Unit

Later plans

The mustard gas stockpile was enlarged in 1940-1941 to help repel a possible Nazi German invasion in 1940–1941, and had there been an invasion may have also deployed it against German cities. General Alan Brooke, in command of British anti-invasion preparations of World War II said that he "...had every intention of using sprayed mustard gas on the beaches" in an annotation in his diary. The British manufactured mustard, chlorine, lewisite, phosgene and Paris Green and stored it at airfields and depots for use on the beaches.

Winston Churchill issued a memorandum advocating a chemical strike on German cities using poison gas and possibly anthrax. Although the idea was rejected, it has provoked debate. In July 1944, fearing that rocket attacks on London would get even worse and that he only use it if it was "life or death for us" or would "shorten the war by a year", Churchill wrote a secret memorandum asking his military chiefs to "think very seriously over this question of using poison gas." He said "it is absurd to consider morality on this topic when everybody used it in the last war without a word of complaint..." and that:

I should be prepared to do anything [Churchill's emphasis] that would hit the enemy in a murderous place. I may certainly have to ask you to support me in using poison gas. We could drench the cities of the Ruhr and many other cities in Germany ..., We could stop all work at the flying bombs starting points.... and if we do it, let us do it one hundred per cent.

— Winston Churchill, 'Most Secret' PRIME MINISTER'S PERSONAL MINUTE to the Chiefs of Staff, 6 July 1944

The Joint Planning Staff (JPS), however, advised against the use of gas because it would inevitably provoke Germany to retaliate with gas. They argued that this would be to the Allies' disadvantage in France both for military reasons and because it might "seriously impair our relations with the civilian population when it became generally known that chemical warfare was first employed by us." The JPS had similar concerns about public morale in Britain, fearing that people might become resentful if they felt a gas war could have been avoided. The Chiefs of Staff also warned that the Nazis would have no particular "difficulty in holding down the cowed German population, if they were subjected to gas attack," whereas the British population "are in no such inarticulate condition." Also that the German might also use Allied prisoners as workers in contaminated areas causing "great public concern".

Churchill responded to this advice by saying:

I am not at all convinced by this negative report. But clearly I cannot make head against the parsons and the warriors at the same time. The matter should be kept under review and brought up again when things get worse.

At the same time, the JPS examined the case of using anthrax bioweapons against six large German cities but only ruled this out on the grounds that the anthrax bombs were not yet available. A large batch of aerial bombs were ordered, but by the time the US factory was ready to produce them, they were deemed unnecessary since the war in Europe was almost over.

Novelist Robert Harris and broadcaster Jeremy Paxman argue that as soon as another weapon of mass destruction – the atomic bomb – became available, and offered a chance to shorten the war, the Americans used it. "Why, from an ethical or political point of view, should germ warfare have been regarded any differently? [by British]."

As the end of the war was sufficiently in sight, British poison gas production was terminated following a request from the Chiefs of Staff Committee in February 1945.

Post-World War II

From 1939 to 1989 experiments on chemical weapons including nerve agents and countermeasures were carried out at the Porton Down research establishment. Although volunteers were used, many ex-servicemen complained about suffering long term illnesses after taking part in the tests. It was alleged that before volunteering they were not provided with adequate information about the experiments and the risk, in breach of the Nuremberg Code of 1947. This became the subject of a lengthy police investigation called Operation Antler.

From 1950, a Chemical Defence Establishment was established as CDE Nancekuke for small-scale chemical agent production. A pilot production facility for Sarin was built, which produced about 20 tons of the nerve agent from 1954 until 1956. A full-scale production plant was planned, but with the 1956 decision to end the United Kingdom's offensive chemical weapons programme it was never built. Nancekuke was mothballed, but was maintained through the 1960s and 1970s in a state whereby production of chemical weapons could easily re-commence if required.

In the early 1980s the government took the view that the lack of a European chemical weapons retaliatory capability was a "major gap in NATO's armoury". However the political difficulties of addressing this prevented any redevelopment of a British chemical weapons capability.

An inquest was opened on 5 May 2004 into the death on 6 May 1953 of a serviceman, Ronald Maddison, during an experiment using sarin. His death had earlier been found by a private Ministry of Defence inquest to have been as a result of "misadventure" but this was quashed by the High Court in 2002. The 2004 hearing closed on 15 November, after a jury found that the cause of Maddison's death was "application of a nerve agent in a non-therapeutic experiment".

Carpet bombing

From Wikipedia, the free encyclopedia

 

 

The first carpet bombing from air in history was the Bombing of Barcelona. 1300 people were killed in 3 days, in March 16-18th, 1938

 

On 14 May 1940 at 1:22 pm, in the Rotterdam Blitz, German bombers set the entire inner city ablaze, killing 814 inhabitants

 

Wesel was 97% destroyed before it was finally taken by Allied troops in 1945

Carpet bombing, also known as saturation bombing, is a large area bombardment done in a progressive manner to inflict damage in every part of a selected area of land. The phrase evokes the image of explosions completely covering an area, in the same way that a carpet covers a floor. Carpet bombing is usually achieved by dropping many unguided bombs.

Carpet bombing of cities, towns, villages, or other areas containing a concentration of civilians is considered a war crime as of Article 51 of the 1977 Protocol I of the Geneva Conventions.

The term obliteration bombing is sometimes used to describe especially intensified bombing with the intention of destroying a city or a large part of the city. The term area bombing refers to indiscriminate bombing of an area and also encompasses cases of carpet bombing, including obliteration bombing. It was used in that sense especially during World War II.

Early history

One of the first cases of carpet bombing was by the Nazi German Condor Legion during the Spanish Civil War against Republican infantry during the Battle of El Mazuco, fought between 6 and 22 September 1937, where the targeted troops were dispersed on rocky slopes and the Condor Legion learned that carpet bombing was not very effective in such terrain.

However, from 16 through 18 March 1938, the Bombing of Barcelona took place successfully, when a series of Fascist Italian and Nazi German airstrikes killed up to 1,300 people and left at least 2,000 wounded. They were carefully designed and recorded, gathering crucial information in preparation for the European War that was around the corner. It is considered the first carpet bombing from air in history, and precedent to several such bombings in World War II carried out by both parties.

During World War II

In the European Theatre, the first city to suffer heavily from aerial bombardment was Warsaw, on 25 September 1939. Continuing this trend in warfare, the Rotterdam Blitz was an aerial bombardment of Rotterdam by 90 bombers of the German Air Force on 14 May 1940, during the German invasion of the Netherlands. The objective was to support the German assault on the city, break Dutch resistance, and force the Dutch to surrender. Despite a ceasefire, the bombing destroyed almost the entire historic city centre, killing nearly nine hundred civilians and leaving 30,000 people homeless. The destructive success of the bombing led the Oberkommando der Luftwaffe (OKL) to threaten to destroy the city of Utrecht if the Dutch Government did not surrender. The Dutch capitulated early the next morning.

As the war progressed, the Battle of Britain developed from a fight for air supremacy into the strategic and aerial bombing of London, Coventry and other British cities. In retaliation for this, the British built up the RAF Bomber Command, which was capable of delivering many thousands of tons of bombs onto a single target, in spite of heavy initial bomber casualties in 1940. The bomber force was then wielded by Arthur Travers Harris in an effort to break German morale and obtain the surrender which Douhet had predicted 15 years earlier. The United States joined the war and the USAAF greatly reinforced the campaign, bringing in the Eighth Air Force into the European Theatre. Many cities, both large and small, were virtually destroyed by Allied bombing. Cologne, Berlin, Hamburg and Dresden are among the most infamous, the latter two developing firestorms. W. G. Sebald's book, On the Natural History of Destruction, comments on the carpet bombing of German cities and asks why it does not play a larger part in the German national consciousness, and why virtually no German authors have written about the events. Despite the lack of literary coverage, a style of film, the rubble film, shot among the urban debris and depicting the gritty lives of those who had to rebuild the destroyed cities, developed in the years after the end of World War II.

Carpet bombing was also used as close air support (as "flying artillery") for ground operations. Massive bombing was concentrated in a narrow and shallow area of the front (a few kilometers by a few hundred meters deep), closely coordinated with the advance of friendly troops. The first successful use of the technique was on 6 May 1943, at the end of the Tunisia Campaign. Carried out under Sir Arthur Tedder, it was hailed by the press as Tedder's bomb-carpet (or Tedder's carpet). The bombing was concentrated in a four by three-mile area, preparing the way for the First Army. This tactic was later used in many cases in the Normandy Campaign; for example, in the Battle for Caen.

In the Pacific War, carpet bombing was used extensively against Japanese civilian population centers, such as Tokyo. On the night of 9–10 March 1945, 334 B-29 Superfortress heavy bombers were directed to attack the most heavily populated civilian sectors of Tokyo. In just one night, over 100,000 people burned to death from a heavy bombardment of incendiary bombs, comparable to the wartime number of U.S. casualties in the entire Pacific theater. Another 100,000 to one million Japanese were left homeless. These attacks were followed by similar ones against Kobe, Osaka, and Nagoya, as well as other sectors of Tokyo, where over 9,373 tons of incendiary bombs were dropped on civilian and military targets. By the time of the dropping of the atomic bombs on Hiroshima and Nagasaki, light and medium bombers were being directed to bomb targets of convenience, as most urban areas had already been destroyed. In the 9-month long civilian bombing campaign, over 400,000 Japanese civilians died.

Vietnam War

During the Vietnam War, with the escalating situation in Southeast Asia, twenty-eight B-52Fs were fitted with external racks for twenty-four 750-pound (340 kg) bombs under project South Bay in June 1964; an additional forty-six aircraft received similar modifications under project Sun Bath. In March 1965, the United States commenced Operation Rolling Thunder. The first combat mission, Operation Arc Light, was flown by B-52Fs on 18 June 1965, when 30 bombers of the 9th and 441st Bombardment Squadrons struck a communist stronghold near the Bến Cát District in South Vietnam. The first wave of bombers arrived too early at a designated rendezvous point, and while maneuvering to maintain station, two B-52s collided, which resulted in the loss of both bombers and eight crewmen. The remaining bombers, minus one more that turned back for mechanical problems, continued toward the target. Twenty-seven Stratofortresses dropped on a one-mile by two-mile target box from between 19,000 and 22,000 feet, a little more than 50% of the bombs falling within the target zone. The force returned to Andersen AFB except for one bomber with electrical problems that recovered to Clark AFB, the mission having lasted 13 hours. Post-strike assessment by teams of South Vietnamese troops with American advisors found evidence that the VC had departed the area before the raid, and it was suspected that infiltration of the south's forces may have tipped off the north because of the ARVN troops involved in the post-strike inspection.

B-52F releasing its payload of bombs over Vietnam

The B-52s were restricted to bombing suspected Communist bases in relatively uninhabited sections, because their potency approached that of a tactical nuclear weapon. A formation of six B-52s, dropping their bombs from 30,000 feet, could "take out"... almost everything within a "box" approximately five-eights mile wide by two miles long. Whenever Arc Light struck ... in the vicinity of Saigon, the city woke from the tremor..

Neil Sheehan, war correspondent, writing before the mass attacks to heavily populated cities including North Vietnam's capital.

Beginning in late 1965, a number of B-52Ds underwent Big Belly modifications to increase bomb capacity for carpet bombings. While the external payload remained at twenty-four 500-pound (227 kg) or 750-pound (340 kg) bombs, the internal capacity increased from twenty-seven to eighty-four 500-pound bombs or from twenty-seven to forty-two 750-pound bombs. The modification created enough capacity for a total of 60,000 pounds (27,215 kg) in one hundred eight bombs. Thus modified, B-52Ds could carry 22,000 pounds (9,980 kg) more than B-52Fs. Designed to replace B-52Fs, modified B-52Ds entered combat in April 1966 flying from Andersen Air Force Base, Guam. Each bombing mission lasted 10 to 12 hours with an aerial refueling by KC-135 Stratotankers. In spring 1967, the aircraft began flying from U Tapao Airfield in Thailand giving the aircraft the advantage of not requiring in-flight refueling.

The zenith of B-52 attacks in Vietnam was Operation Linebacker II (sometimes referred to as the Christmas Bombing) which consisted of waves of B-52s (mostly D models, but some Gs without jamming equipment and with a smaller bomb load). Over 12 days, B-52s flew 729 sorties and dropped 15,237 tons of bombs on Hanoi, Haiphong, and other targets. Originally 42 B-52s were committed to the war; however, numbers were frequently twice this figure.

Aerial bombardment and international law

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Aerial_bombardment_and_international_law 

Air warfare must comply with laws and customs of war, including international humanitarian law by protecting the victims of the conflict and refraining from attacks on protected persons.

These restraints on aerial warfare are covered by the general laws of war, because unlike war on land and at sea—which are specifically covered by rules such as the 1907 Hague Convention and Protocol I additional to the Geneva Conventions, which contain pertinent restrictions, prohibitions and guidelines—there are no treaties specific to aerial warfare.

To be legal, aerial operations must comply with the principles of humanitarian law: military necessity, distinction, and proportionality: An attack or action must be intended to help in the military defeat of the enemy; it must be an attack on a military objective, and the harm caused to civilians or civilian property must be proportional and not excessive in relation to the concrete and direct military advantage anticipated.

International law up to 1945

International law relating to aerial bombardment before and during World War II rests on the treaties of 1864, 1899, and 1907, which constituted the definition of most of the laws of war at that time — which, despite repeated diplomatic attempts, was not updated in the immediate run up to World War II. The most relevant of these treaties is the Hague Convention of 1907 because it was the last treaty ratified before 1939 which specify the laws of war regarding the use of bombardment. In the Hague Convention of 1907, there are two which have a direct bearing on this issue of bombardment. These are "Laws of War: Laws and Customs of War on Land (Hague IV); 18 October 1907" and "Laws of War: Bombardment by Naval Forces in Time of War (Hague IX); 18 October 1907". It is significant that there is a different treaty which should be invoked for bombardment of land by land (Hague IV) and of land by sea (Hague IX). Hague IV, which reaffirmed and updated Hague II (1899), contains the following clauses:

Article 25: The attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are undefended is prohibited.

Article 26: The officer in command of an attacking force must, before commencing a bombardment, except in cases of assault, do all in his power to warn the authorities.
Article 27: In sieges and bombardments all necessary steps must be taken to spare, as far as possible, buildings dedicated to religion, art, science, or charitable purposes, historic monuments, hospitals, and places where the sick and wounded are collected, provided they are not being used at the time for military purposes.

It is the duty of the besieged to indicate the presence of such buildings or places by distinctive and visible signs, which shall be notified to the enemy beforehand.

Although the 1907 Hague Conventions IV – The Laws and Customs of War on Land and IX – Bombardment by Naval Forces in Time of War prohibited the bombardment of undefended places, there was no international prohibition against indiscriminate bombardment of non-combatants in defended places, a shortcoming in the rules that was greatly exacerbated by aerial bombardment. With the rise of aerial warfare, non-combatants became extremely vulnerable and were inevitably collateral targets in such warfare potentially on a much larger scale than previously.

German airship Schütte Lanz SL2 bombing Warsaw in 1914

World War I saw the first time strategic bombing was used when German Zeppelins and aircraft indiscriminately dropped bombs on cities in Britain and France. These nations who fought against Germany and its allies in the war retaliated with their own air raids. A few years after World War I, a draft convention was proposed in 1923: The Hague Rules of Air Warfare. There are number of articles which would have directly affected how nations used aerial bombardment and defended against it; these are articles 18, 22 and 24. The law was, however, never adopted in legally binding form as it was criticized by all major powers as being unrealistic.

The subordination of the law of air warfare to the law of ground warfare was arguably established by the Greco-German arbitration tribunal of 1927–30. It found that the 1907 Hague Convention on "The Laws and Customs of War on Land" applied to the German attacks in Greece during World War I: This concerned both Article 25 and Article 26.

Jefferson Reynolds in an article The U.S. Air Force Law Review argues that "if international law is not enforced, persistent violations can conceivably be adopted as customary practice, permitting conduct that was once prohibited." Even if the Greco-German arbitration tribunal findings had established the rules for aerial bombardment, by 1945, the belligerents of World War II had ignored the preliminary bombardment procedures that the Greco-German arbitration tribunal had recognized.

German Heinkel He 111 planes bombing Warsaw (September 1939)

The German bombings of Guernica and Durango in Spain in 1937 during the Spanish Civil War and the Japanese aerial attacks on crowded Chinese cities during the Second Sino-Japanese War in 1937–38 attracted worldwide condemnation, prompting the League of Nations to pass a resolution that called for the protection of civilian populations against bombardment from the air. In response to the resolution passed by the League of Nations, a draft convention in Amsterdam of 1938 would have provided specific definitions of what constituted an "undefended" town, excessive civilian casualties and appropriate warning. This draft convention makes the standard of being undefended quite high – any military units or anti-aircraft within the radius qualifies a town as defended. This convention, like the 1923 draft, was not ratified, nor even close to being ratified, when hostilities broke out in Europe in 1939. While the two conventions offer a guideline to what the belligerent powers were considering before the war, neither of these documents came to be legally binding.

At the start of World War II in 1939, following an appeal by Franklin D. Roosevelt, President of the neutral United States, the major European powers, including Britain and Germany, agreed not to bomb civilian targets outside combat zones: Britain agreeing provided that the other powers also refrained. (see the policy on strategic bombing at the start of the World War II). However, this was not honored as belligerents of both sides in the war adopted a policy of indiscriminate bombing of enemy cities. Throughout World War II, cities like Chongqing, Warsaw, Rotterdam, London, Coventry, Hamburg, Dresden, Tokyo, Hiroshima, and Nagasaki were struck by aerial bombardment, causing untold numbers of destruction of buildings and the deaths of tens of thousand civilians.

After World War II, the massive destruction of non-combatant targets inflicted during the war prompted the victorious Allies to address the issue when the Nuremberg Charter was enacted, establishing the procedures and laws by which the Nuremberg Trials were to be conducted. Article 6(b) of the Charter thus condemned the "wanton destruction of cities, towns or villages, or devastation not justified by military necessity" and classified it as a violation of the laws or customs of war, therefore, making it a war crime. This provision was similarly made at the Tokyo Trials to try Japanese military and civilian leaders for illegal conducts committed during the Pacific War with the enactment of the Tokyo Charter. However, due to the absence of positive or specific customary international humanitarian law prohibiting illegal conducts of aerial warfare in World War II, the indiscriminate bombing of enemy cities was excluded from the category of war crimes at the Nuremberg and Tokyo Trials, therefore, no Axis officers and leaders were prosecuted for authorizing this practice. Furthermore, the United Nations War Crimes Commission received no notice of records of trial concerning the illegal conduct of air warfare. Chris Jochnick and Roger Normand in their article The Legitimation of Violence 1: A Critical History of the Laws of War explains that: "By leaving out morale bombing and other attacks on civilians unchallenged, the Tribunal conferred legal legitimacy on such practices."

Mushroom cloud from the atomic explosion over Nagasaki (August 9, 1945)

In 1963, the atomic bombings of Hiroshima and Nagasaki were the subject of a Japanese judicial review in Ryuichi Shimoda et al. v. The State. The review draws several distinctions which are pertinent to both conventional and atomic aerial bombardment. Based on international law found in Hague Convention of 1907 IV – The Laws and Customs of War on Land and IX – Bombardment by Naval Forces in Time of War, and the Hague Draft Rules of Air Warfare of 1922–1923 the Court drew a distinction between "Targeted Aerial Bombardment" and indiscriminate area bombardment, that the court called "Blind Aerial Bombardment", and also a distinction between a defended and an undefended city. "In principle, a defended city is a city which resists an attempt at occupation by land forces. A city even with defence installations and armed forces cannot be said to be a defended city if it is far away from the battlefield and is not in immediate danger of occupation by the enemy." The court ruled that blind aerial bombardment is permitted only in the immediate vicinity of the operations of land forces and that only targeted aerial bombardment of military installations is permitted further from the front. It also ruled that, in such an event, the incidental death of civilians and the destruction of civilian property during targeted aerial bombardment was not unlawful. The court acknowledged that the concept of a military objective was enlarged under conditions of total war, but stated that the distinction between the two did not disappear. The court also ruled that when military targets were concentrated in a comparatively small area, and where defence installations against air raids were very strong, that when the destruction of non-military objectives is small in proportion to the large military interests, or necessity, such destruction is lawful. Thus, in the judgement of the Court, because of the immense power of the atom bombs, and the distance from enemy land forces, the atomic bombings of both Hiroshima and Nagasaki "was an illegal act of hostilities under international law as it existed at that time, as an indiscriminate bombardment of undefended cities".

Not all governments and scholars of international law agree with the analysis and conclusions of the Shimoda review, because it was not based on positive international humanitarian law. Colonel Javier Guisández Gómez, at the International Institute of Humanitarian Law in San Remo, points out:

In examining these events [Anti-city strategy/blitz] in the light of international humanitarian law, it should be borne in mind that during the Second World War there was no agreement, treaty, convention or any other instrument governing the protection of the civilian population or civilian property, as the Conventions then in force dealt only with the protection of the wounded and the sick on the battlefield and in naval warfare, hospital ships, the laws and customs of war and the protection of prisoners of war.

John R. Bolton, (Under Secretary of State for Arms Control and International Security Affairs (2001–2005) and U.S. Permanent Representative to the United Nations (2005–2006)), explained in 2001 why the USA should not adhere to the Rome Statute of the International Criminal Court:

A fair reading of the [Rome Statute], for example, leaves the objective observer unable to answer with confidence whether the United States was guilty of war crimes for its aerial bombing campaigns over Germany and Japan in World War II. Indeed, if anything, a straightforward reading of the language probably indicates that the court would find the United States guilty. A fortiori, these provisions seem to imply that the United States would have been guilty of a war crime for dropping atomic bombs on Hiroshima and Nagasaki. This is intolerable and unacceptable.

International law since 1945

In the post war environment, a series of treaties governing the laws of war were adopted starting in 1949. These Geneva Conventions would come into force, in no small part, because of a general reaction against the practices of the Second World War. Although the Fourth Geneva Convention attempted to erect some legal defenses for civilians in time of war, the bulk of the Fourth Convention devoted to explicating civilian rights in occupied territories, and no explicit attention is paid to the problems of bombardment.

In 1977, Protocol I was adopted as an amendment to the Geneva Conventions, prohibiting the deliberate or indiscriminate attack of civilians and civilian objects, even if the area contained military objectives, and the attacking force must take precautions and steps to spare the lives of civilians and civilian objects as possible. However, forces occupying near densely populated areas must avoid locating military objectives near or in densely populated areas and endeavor to remove civilians from the vicinity of military objectives. Failure to do so would cause a higher civilian death toll resulting from bombardment by the attacking force and the defenders would be held responsible, even criminally liable, for these deaths. This issue was addressed because drafters of Protocol I pointed out historical examples such as Japan in World War II who often dispersed legitimate military and industrial targets (almost two-thirds of production was from small factories of thirty or fewer persons or in wooden homes, which were clustered around the factories) throughout urban areas in many of its cities either with the sole purpose of preventing enemy forces from bombing these targets or using its civilian casualties caused by enemy bombardment as propaganda value against the enemy. This move made Japan vulnerable to area bombardment and the U.S. Army Air Forces (USAAF) adopted a policy of carpetbombing which destroyed 69 Japanese cities with either incendiary bombs or atomic bombs, with the deaths of 381,000-500,000 Japanese people.

However, Protocol I also states that locating military objectives near civilians "shall not release the Parties to the conflict from their legal obligations with respect to the civilian population and civilians." (Article 51, Para 8)

The International Court of Justice gave an advisory opinion in July 1996 on the Legality of the Threat Or Use Of Nuclear Weapons. The court ruled that "[t]here is in neither customary nor international law any comprehensive and universal prohibition of the threat or use of nuclear weapons." However, by a split vote, it also found that "[t]he threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict." The Court stated that it could not definitively conclude whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defense, in which the very survival of the state would be at stake.