Double Cross: Britain’s WWII Deception Unit

My fellow writer Tom Burrell has just written a great post about the US Army’s deception unit in the Second World War, so I thought I’d throw in a piece about one of its British equivalents – the Twenty Committee. Unlike the 23rd Headquarters Special Troops in the US Army, this wasn’t a military unit – however shadowy; it was the center of a whole tangled web of operations.

The Twenty Committee was named after the Roman numeral for 20, which is XX – a double cross. The overall British deception plan was known as the XX System and was carried out by a multitude of different units and organizations, so it needed a central authority to make sure its elements didn’t interfere with each other’s work. The Twenty Committee, run by tennis player and Oxford professor John Masterman, took on that job. Masterman joined the Army as an Intelligence Corps officer in 1939 but soon found himself working for MI5. The main task of MI5 was counterintelligence, and that’s how the XX System began – tracking down and turning German spies.

Through the war, most people in Britain believed there must be a huge, efficient network of German spies operating in the UK. MI5 were quite happy to let them think that, and in fact the Germans believed pretty much exactly the same. After all, from the beginning to the end of the war they received a steady flow of reports from the agents they’d sent across the English Channel.

What they didn’t know was that every single German spy dispatched to the UK was quickly captured, apart from one who committed suicide as the net closed in on him. Once they were in the hands of MI5, they were quickly interrogated, to see if they could be persuaded to turn – and whether or not they were worth the effort. Some were judged to be too loyal or too useless, and quietly imprisoned or executed. Others agreed to change sides. In one case, two agents, who were personal friends, were captured together. One was told his friend’s life would be spared if he cooperated, which he agreed to do. MI5 then told the other that his friend had betrayed him; in a fury he decided to work for the British.

John Cecil Masterman
John Cecil Masterman

The Germans never suspected that their agents had been so efficiently compromised. One great advantage the British had was that they could read German message traffic, thanks to their cracking of the Enigma machine, and that included the traffic of Admiral Canaris’ secret service. Whenever the Abwehr seemed to be getting suspicious of an agent, the Twenty Committee would arrange for them to supply some genuine, and verifiable, intelligence. Most of the German agents were awarded the Iron Cross through the war for their effectiveness and loyalty.

One of the greatest achievements of the XX System was to reduce the damage caused in the last years of the war by Germany’s “Vengeance weapons,” the V1 cruise missile and V2 ballistic missile. These were powerful and hard to intercept – the V2 was impossible to intercept – so Masterman launched Operation Crossbow to deceive the Germans about where they were landing. V1 hits in north London were reported – in exaggerated numbers – while impacts in the south were covered up. As reports trickled back from their agents, the Germans decided that the weapons were overflying their targets, and programmed them to dive a few miles earlier – with the result that most of them landed in fields short of London. When V2s started landing, the British sent reports that used actual impact sites and times, but paired them wrongly. The Germans knew the time the missiles were launched, and roughly when they would impact. By pairing a missile that had landed south or east of the capital with the impact time of one that had actually hit its target, XX managed to shift the Germans’ aim away from the city so they were blowing up farmland again.

As the war went on, the Twenty Committee was involved in many more operations, including creating General Patton’s phantom First United States Army Group in Kent. Even when Allied troops landed in Normandy, the Germans still believed that the “real” invasion would come when FUSAG crossed the Pas de Calais. In a final twist, XX then sent messages to the Abwehr claiming that the Calais invasion had been cancelled because of the unexpected success of the “diversionary attack” in Normandy. The Germans believed these reports, and kept trusting their agents right to the very end.

Deception is a war-winning tactic if it’s used properly but, in modern western armies, we pay lip service to it far too often. If commanders add a deception plan at all, it’s usually an afterthought, with too few resources available to make it look credible. The Russians, and their clients, have never forgotten its importance – who can forget the embarrassing results of NATO’s bombing in Kosovo, when hundreds of expensive weapons were dropped on wooden tanks? That should be a lesson to us that we still need the skills of XX and the 23rd’s Ghost Troops.

Disclaimer: The content in this article is the opinion of the writer and does not necessarily reflect the policies or opinions of US Patriot Tactical.

Fergus Mason

Fergus Mason grew up in the west of Scotland. After attending university he spent 14 years in the British Army and served in Bosnia, Northern Ireland, Kosovo and Iraq. Afterwards, he went to Afghanistan as a contractor, where he worked in Kabul, Mazar-e-Sharif and Camp Leatherneck. He now writes on a variety of topics including current affairs and military matters.
Fergus Mason

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