Churchill’s secret chemical war

Had the German invasion of Britain gone ahead in 1940 – with Churchill deploying mustard gas – the Second World War would have taken a very different turn, writes Patrick Cockburn

The French city of Rouen enveloped by smoke and fire during the German invasion in 1940 (Getty)

In the summer of 1940, Britain made hurried plans to resist a German invasion that had suddenly become feasible after the German victory in France. The operation was code-named Sea Lion and, in its final form, it envisaged a landing of some 90,000 troops on the southeast coast of England between Folkestone and Brighton. The invasion force was to cross the channel in a heterogeneous fleet of motorised barges, steamers, tugs and motorboats collected from all over western Europe.

Historians overwhelmingly dismiss the chances of Sea Lion succeeding in the face of the Royal Navy’s dominance in the Channel and the failure of the Luftwaffe to defeat the RAF in the skies overhead. They argue that it might have been possible for the Germans to land the first wave of an invasion force on a narrow front, given a foggy night and a lot of luck. But, even if it had achieved initial success, the invasion force would have been cut off from reinforcements and supplies by the navy, making a German failure inevitable.

Such an outcome still looks highly probable 80 years later, but ships, planes and ground forces were not the only means by which the British high command intended to stop the Germans on the beaches. It only became clear many years after the war that the British political and military leadership intended to use poison gas sprayed from aircraft to strike at the German troops as soon as they got ashore. On 30 June Winston Churchill wrote in a memo: “Supposing lodgements were effected on our coast, there could be no better points for application of mustard [gas] than these beaches and lodgements.”

The prime minister was not alone in seeing poison gas as a potentially decisive weapon against the Germans in the aftermath of Dunkirk. On 15 June, two days after the evacuation of the last British troops, the chief of imperial general staff, Sir John Dill, wrote a paper titled “The Use of Gas in Home Defence”, in which he argued that “enemy forces crowded on the beaches, with the confusion inevitable on first landing, would present a splendid target”. He believed that gas sprayed by the RAF in such circumstances might be more effective than high explosives. It would have the further advantage of permanently contaminating beaches and exits from them, hampering the German assault.

Other British generals did not agree, saying that the use of gas by Britain, in breach of pre-war protocols forbidding their use, would be morally and politically damaging. It would also invite German retaliation in kind by a powerful German bomber force from nearby airfields in France and the Low Countries. But Churchill was adamant that poison gas would and should be used in maximum quantities and he later derided those who were against doing so as a set of “psalm-singing uniformed defeatists”.

A student at Scotland’s Civil Defence Training School opens a steel bottle containing mustard gas (Getty)

There was more to this than a short-term panicky British response to the feeble state of their defences after the British Army had lost 40,000 prisoners and almost all of its heavy equipment in battles in France.

Churchill had been shocked to discover that the British poison gas stocks were low: only 450 tons of mustard gas and some phosgene. He demanded that they be swiftly built up along with the means to deliver them. During the Battle of Britain, bomber aircraft were being withdrawn to Scotland to be re-equipped with tanks to hold the mustard gas and their crews retrained in order to spray the beaches. More gas was ordered from factories in the US and at the US embassy in London the military attaché was surprised to find how much effort Britain was putting into developing its chemical warfare capacity. General Alan Brooke, the intelligent and experienced commander of British forces in the southeast of England, wrote after the war that, if the Germans had landed, he “had every intention of using sprayed mustard gas on the beaches”.

Had the Germans landed, even in small numbers, and gas had been used against them, the outcome of the Second World War might not have changed, but the means by which it was fought would have been transformed. The Germans, who had 20 times as much poison gas as the British, would certainly have retaliated against civilian as well as military targets. The millions of gas masks, which people in Britain had been instructed to carry at all times, would have been put to the test. Chemical warfare would have inevitably spread to other fronts.

The image of British soldiers blinded by a mustard gas attack by the Germans in Bethune, France, that was used by US artist John Singer Sargent for his painting ‘Gassed’ (Getty)

An unexpected feature of the Second World War is that poison gas was never used by any of the contending armies. Given its widespread deployment in the First World War, this was surprising since both conflicts were fought with equal savagery and lack of restraint. Germany, the UK, France, the US, the Soviet Union and Japan all had stocks of gas, but they never used them. Fear of retaliation was one cause of this, but there was nothing inevitable about the non-use of chemical weapons. “It was nearly used, but wasn’t because of the precise military circumstances prevailing at the time,” wrote Robert Harris and Jeremy Paxman in A Higher Form of Killing: The Secret Story of Chemical and Biological Warfare. Published in 1982, it was the first book to use previously secret government papers, several of which are quoted in this article, spelling out its extensive plans to use chemical weapons to beat back a German invasion in 1940. Churchill had written that “they would have used terror and we were prepared to go to all lengths”. The last cryptic words of the sentence referred to chemical warfare.

Winston Churchill, who believed poison gas could be a potentially decisive weapon against the Germans, giving a speech at County Hall in London (Getty)

Since Germany did not, in the event, invade Britain and because such an invasion, if it had occurred, would likely have failed, British plans to use poison gas against German beachheads may seem chimerical. But Hitler’s ultimate failure to give the order for the invasion does not mean that he never intended to do so or that there was anything phoney about the threat. He said in the course of a conversation at his headquarters in 1943 that he much regretted “having allowed himself to be talked out of [Operation] Sea Lion by the navy in the autumn of 1940”. Hitler was a gambler and in 1940 a terrifyingly successful one, who might have given the order for the invasion, regardless of contrary opinions from the German navy.

It would be wrong to underrate the drive and resourcefulness with which, in a matter of weeks and starting from scratch, the Germans equipped and assembled the craft they needed. It was a prodigious feat of organisation

German military commanders may have had their doubts, but there was nothing phoney about the elaborate and highly organised preparations to cross the Channel. Hitler issued Directive No 16 for Sea Lion on 16 July, but work on the operation had started two weeks earlier. “It would be wrong to underrate the drive and resourcefulness with which, in a matter of weeks and starting from scratch, the Germans equipped and assembled the craft they needed,” wrote Peter Fleming in Invasion 1940. “It was a prodigious feat of organisation.”

After their victories over the previous year, the Germans controlled the economic resources of most of western Europe. Even so, it was not easy to commandeer 1,722 barges, 155 transports, 471 tugs and 1,161 motorboats and move them to the French Channel ports. Many barges had to be motorised and converted from river to sea use and prepared for an operation in which they would have to cross and re-cross the Channel. They would inevitably have come under attack from an undefeated British navy that would not have been deterred by air attack, even if it suffered heavy losses.\

(Wikimedia Commons (Wikimedia Commons)

Hitler could see that an invasion was risky, but he had taken such risks in the past and succeeded. He knew that the biggest obstacle to a seaborne invasion was that Germany did not control the sea lanes off the invasion beaches. But this is not quite the decisive argument against an invasion as it is sometimes portrayed, given that Germany had successfully invaded and occupied Norway without command of the sea earlier in 1940. It was to do so again in Crete in 1941. It could be argued that in Norway and Crete, unlike England in 1940, the Luftwaffe had overwhelming control of the air. But the Germans would have only needed to control the airspace over the Channel between France and the 60-mile long stretch of coast between Brighton and Folkestone. In addition, there was the danger that German troops would capture airfields in Kent and East Sussex and use them to bring in supplies and reinforcements. They were to do this successfully in the battle for Crete the following year.

Pilots relax on the grass beside their Hawker Hurricane Mk1 fighters during the Battle of Britain at RAF Hawkinge near Folkestone (Getty)

It is an unlikely scenario but it is a possible one and, if it had happened, it would have precipitated the use of mustard gas by the British. The Germans would be at their weakest during the first chaotic hours after their landing. Their first wave would only number 60,000 lightly armed soldiers. Deluging the beachheads with gas might have been the best way of stopping them consolidating their positions. The British, for all Churchill’s rhetorical defiance, were conscious of how weak they were militarily after losing so many tanks and so much artillery in France. A sobering appreciation of British military strength at the end of May by the chiefs of staff concluded that, if the Germans got a force ashore, the British Army had “not got the offensive power to drive them out”.

Could poison gas have done the job instead? More than most weapons, it spreads terror because it can blind and asphyxiate within seconds, destroying the lungs and raising giant blisters where it touches the skin. Gas masks and ointments might make the chance of a slow agonising death less likely, but it does not eliminate the prospect. German troops had gas masks and anti-gas equipment, but these were kept in large zinc-lined boxes with other stores and would have to be dragged up the beaches and opened. The British were probably right in thinking that many German soldiers would be without their gas masks as they fought their way forwards.

But could poison gas-spraying aircraft have been as effective as Churchill and others were hoping? Targeting the enemy accurately has always been more difficult than air forces care to admit. Gas warfare is particularly tricky: in the First World War there had been many cases of the wind dispersing the gas or blowing it in the wrong direction. Converted British bombers such as Battles, Blenheims, Wellingtons and Lysanders would have had to fly the length of beaches and coastal areas at a low-level while spraying the deadly gas on the German troops below them. Given that they would simultaneously be under attack from German fighter aircraft, the likelihood of them successfully carrying out their mission would be highly dubious. Pre-war advocates of bomber aircraft as a war-winning weapon were shown up by grim experience to have exaggerated its pinpoint accuracy. Yet this wishful thinking was not so evident at an early stage of the war. “Low spray attacks,” wrote the inspector of chemical warfare in a passage quoted by Harris and Paxman, “on an enemy approaching our shores in open boats or after landing are likely to be effective if frequently repeated, and will ultimately result in 100 per cent casualties among the men hit by the spray.” If the enemy were not wearing eye shields then a considerable portion would be blinded, according to the inspector.

The effectiveness of poison gas against trained and well-equipped forces would probably have been less than its protagonists imagined. But if there had been an invasion by the Germans and the British had used gas against them, then it is very likely that the Germans would have employed the same tactic against London and other British cities in the Blitz between September 1940 and May 1941. The British would then, in turn, have retaliated against Germany. Gas warfare would have been back in business in the Second as in the First World War. The outcome might have been the same, but the death toll would have been even worse.