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.”