The Double-Cross System or XX System was a World War II counter-espionage and deception operation of the British Security Service (MI5). Nazi agents in Britain – real and false – were captured, turned themselves in or simply announced themselves, and were then used by the British to broadcast mainly disinformation to their Nazi controllers. Its operations were overseen by the Twenty Committee under the chairmanship of John Cecil Masterman; the name of the committee comes from the number 20 in Roman numerals: "XX".
Wilhelm Franz Canaris was a German admiral and the chief of the Abwehr from 1935 to 1944. Canaris was initially a supporter of Adolf Hitler, and the Nazi regime. Following the German invasion of Poland in 1939, however, Canaris turned against Hitler and committed acts of both passive and active resistance during the war.
Operation Fortitude was a military deception operation by the Allied nations as part of Operation Bodyguard, an overall deception strategy during the buildup to the 1944 Normandy landings. Fortitude was divided into two subplans, North and South, and had the aim of misleading the German High Command as to the location of the invasion.
Operation Bodyguard was the code name for a World War II deception strategy employed by the Allied states before the 1944 invasion of northwest Europe. Bodyguard set out an overall stratagem for misleading the Oberkommando der Wehrmacht as to the time and place of the invasion. Planning for Bodyguard was started in 1943 by the London Controlling Section, a department of the war cabinet. They produced a draft strategy, referred to as Plan Jael, which was presented to leaders at the Tehran Conference in late November and, despite scepticism due to the failure of earlier deception strategy, approved on 6 December 1943.
Plan Kathleen, sometimes referred to as the Artus Plan, was a military plan for the invasion of Northern Ireland by Nazi Germany, sanctioned in 1940 by Stephen Hayes, Acting Irish Republican Army (IRA) Chief of Staff.
Reinhard Gehlen was a German career intelligence officer who served the Weimar Republic, Nazi Germany, the U.S. intelligence community, and the NATO-affiliated Federal Republic of Germany during the Cold War.
Kurt Arthur Benno Student was a German general in the Luftwaffe during World War II. An early pioneer of airborne forces, Student was in overall command of developing a paratrooper force to be known as the Fallschirmjäger, and as the most senior member of the Fallschirmjäger, commanded it throughout the war. Student led the first major airborne attack in history, the Battle for The Hague, in May 1940. He also commanded the Fallschirmjäger in its last major airborne operation, the invasion of Crete in May 1941. The operation was a success despite German losses, and led the Allies to hasten the training and development of their own airborne units.
Operation Copperhead was a small military deception operation run by the British during the Second World War. It formed part of Operation Bodyguard, the cover plan for the invasion of Normandy in 1944 and was intended to mislead German intelligence as to the location of General Bernard Montgomery. The operation was conceived by Dudley Clarke in early 1944 after he watched the film Five Graves to Cairo. Following the war M. E. Clifton James wrote a book about the operation, I Was Monty's Double. It was later adapted into a film, with James in the lead role.
Josef Jakobs was a German spy and the last person to be executed at the Tower of London. He was captured shortly after parachuting into the United Kingdom during the Second World War. Convicted of espionage under the Treachery Act 1940, Jakobs was sentenced to death and shot by a military firing squad. He was not hanged since he was captured as an enemy combatant.
Operation Ironside was a Second World War military deception undertaken by the Allies in 1944. It formed part of Operation Bodyguard, a broad strategic deception plan instigated by the Allies throughout the year to help cover the June 1944 invasion of Normandy. Ironside supported the overall deception by suggesting to the Germans that the Allies would subsequently land along the Bay of Biscay. It complemented efforts to deceive the Germans into believing that the Allies would also land in southern France at this time. Bordeaux was an important port for the German war effort and had already been a target of commando raids two years earlier. Ironside intended to play on German fears of an invasion in the region, with the aim of tying down defensive forces following Operation Overlord in June 1944.
First United States Army Group was a fictitious Allied Army Group in World War II prior to D-Day, part of Operation Quicksilver, created to deceive the Germans about where the Allies would land in France. To attract Axis attention, prominent US general George S. Patton was placed in command of the fabricated formation.
The 80th Infantry (Reserve) Division was an infantry division of the British Army formed at the beginning of 1943, during the Second World War. For the twenty months that the division existed, it was a training formation. It was made responsible for providing final tactical and field training to soldiers who had already passed their initial training. After five additional weeks of training, the soldiers would be posted to fighting formations overseas. Notably, the division was used as a source of reinforcements for the 21st Army Group, which was fighting in Normandy. After all available troops left the United Kingdom for France, the division was disbanded.
Halina Szymańska (1906–1989) was a Polish spy, working for the British government, known as the Allies' conduit to Nazi German Admiral Wilhelm Canaris. She was the wife of Colonel Antoni Szymański, the last prewar Polish military attaché in Berlin, and of later General Kazimierz Wiśniowski.
The London Controlling Section (LCS) was a British secret department established in September 1941, under Oliver Stanley, with a mandate to coordinate Allied strategic military deception during World War II. The LCS was formed within the Joint Planning Staff at the offices of the War Cabinet, which was presided over by Winston Churchill as Prime Minister.
The Abwehr was the German military-intelligence service for the Reichswehr and the Wehrmacht from 1920 to 1945. Although the 1919 Treaty of Versailles prohibited the Weimar Republic from establishing an intelligence organization of their own, they formed an espionage group in 1920 within the Ministry of Defence, calling it the Abwehr. The initial purpose of the Abwehr was defense against foreign espionage: an organizational role that later evolved considerably. Under General Kurt von Schleicher the individual military services' intelligence units were combined and, in 1929, centralized under Schleicher's Ministeramt within the Ministry of Defence, forming the foundation for the more commonly understood manifestation of the Abwehr.
Wulf Dietrich Christian Schmidt, later known as Harry Williamson was a Danish citizen who became a double agent working for Britain against Nazi Germany during the Second World War under the codename Tate. He was part of the Double Cross System, under which all German agents in Britain were controlled by MI5 and used to deceive Germany. Nigel West singled him out as "one of the seven spies who changed the world."
Nathalie "Lily" Sergueiew was a double agent who worked for MI5 during World War II under the codename "Treasure". She played a significant role in the Double-Cross System, particularly by deceiving the Germans about the location of the D-Day landings.
Operation Royal Flush was a military deception employed by the Allied Nations during the Second World War as part of the strategic deception Operation Bodyguard. Royal Flush was a political deception that expanded on the efforts of another Bodyguard deception, Operation Graffham, by emphasising the threat to Norway. It also lent support to parts of Operation Zeppelin via subtle diplomatic overtures to Spain and Turkey. The idea was that information from these neutral countries would filter back to the Abwehr. Planned in April 1944 by Ronald Wingate, Royal Flush was executed throughout June by various Allied ambassadors to the neutral states. During implementation the plan was revised several times to be less extreme in its diplomatic demands. Information from neutral embassies was not well trusted by the Abwehr; as a result, Royal Flush had limited impact on German plans through 1944.
Johann-Nielsen Jebsen, nicknamed "Johnny", was an anti-Nazi German intelligence officer and British double agent during World War II. Jebsen recruited Dušan Popov to the Abwehr and through him later joined the Allied cause. Kidnapped from Lisbon by the Germans shortly before the Normandy landings, Jebsen was tortured in prison and spent time in a concentration camp before disappearing; he was presumed killed at the end of the war.
Alphons Louis Eugene Timmerman was a Belgian ship's steward who became a spy for the German intelligence agency, the Abwehr, during the Second World War. He was captured by the security services upon his arrival in Britain in September 1941. MI5 officers posed as Timmerman in correspondence with the Abwehr in an attempt to deceive them as to the competence of the British security services. This attempt was unsuccessful as German intelligence officers failed to spot deliberate mistakes in the letters, but did help to disprove the Abwehr's previously good reputation for intelligence work. Timmerman admitted to being a spy and was executed at Wandsworth Prison in 1942.
