"Lily" was a French woman of Russian descent, Lily Seyver, who gave a detailed report on the situation of the First Army Group and won the trust of the German intelligence services, and the German intelligence agencies also specifically asked her to go to Spain and provide her with a radio station for direct contact.

"Brutus" is a former Polish Air Force officer, in the summer of 1940 in France organized underground resistance, arrested in November 1944, the German spy agency threatened him to serve Germany with the lives of the remaining 64 members of his group, came to Britain via Spain in July 1942, and immediately surrendered to the British intelligence service, and then with the cooperation of the British intelligence agency, began to send reports to Germany outside London. A total of 123 pieces of information were sent to Germany between January and June 1944, almost every one of which was confirmed by German intelligence to be accurate and deeply believed by the German army.

The British also organized an unusually cunning, even cruel and despicable operation. In July 1944, the Resistance Group, codenamed "Prosperity", which was part of the British Special Operations Service in northern France, was busted by the German Gestapo as a result of Henri Derigou's whistleblowing, and dozens of members of the Resistance, including its head, Francis Sutil, were arrested. The telegraph operator of the "Boom" cell, who was coerced by the Gestapo, continued to maintain contact with the British headquarters, because the telegraph operator's fingering was like a person's handwriting, which was difficult to counterfeit. The operator takes the flight in accordance with the prior regulations do not issue a security password to the headquarters to alarm, the so-called security password is in the specified line of a certain word,

Misspelling or repeating the word on purpose, if the word is not misspelled or repeated in the agreed place, means that the station is under German control. However, despite warnings, Headquarters continued to maintain contact and airdropped large quantities of weapons, explosives, communications equipment, activity funds and even new agents at German request. As soon as these materials and personnel landed, they fell into the hands of the German Gestapo. It is well known that the torture of the Gestapo was intolerable to ordinary people, and all British agents sent to the occupied territories carried highly poisoned drugs in order to commit suicide when they were arrested or when torture could not be endured. The Pope of Rome in the Vatican also issued an amnesty specifically for Christians who could not stand the torture of the Gestapo and committed suicide, pardoning their sins of suicide. Can "prosper" resistance

The team's backbone and later airdropped agents carried non-toxic pills, and after they were captured, they were tortured and tortured, with no way to survive and hopeless, and finally confessed their mission: to attack the German headquarters in Calais, the communications center, the shore artillery, and the power supply system, and cooperate with the Allied landing. The Gestapo was convinced of the veracity of these confessions, most of which were obtained after repeated torture.

Thus the conclusion was drawn that the Allies would land in Calais. In fact, the whistleblower Derigou used this method to gain the trust of the Gestapo under the top secret directives of the London Oversight Service, and thus to break into the German intelligence services. And the Gestapo could not have imagined that the British intelligence services would be so shameless as to provide a single piece of false information at the cost of hundreds of thousands of dollars worth of weapons and equipment and the lives of dozens of loyal subordinates. It is fair to say that these were the most eloquent and weeping heroes of the Normandy landings, who saved the lives of thousands of Allied soldiers and the people of the occupied countries with their lives, the vast majority of whom were executed or sent to death camps by the Gestapo, and Derigou was carried by the French resistance

Death was charged with internal rape. Even before the end of the war, British intelligence sent special personnel to find out the whereabouts of these men, and posthumously awarded some of them medals for their extraordinary courage and heroism in extremely dangerous circumstances

In addition, the French Resistance also played an important role. At the time of the landing on 6 June, BBC radio broadcast a large number of coded instructions to the resistance groups in Normandy, asking them to destroy railways, roads, bridges, and communication lines, and to assist in the Allied landing. On June 9, when the fierce fighting in Normandy was at a critical juncture, the BBC broadcast a large number of coded instructions to the resistance groups in Calais, Belgium, and the Netherlands, asking them to attack the lines of communication and the German command and communication center as planned, and cooperate with the imminent landing in Calais. Since German intelligence had already uncovered 15 underground resistance groups, and according to the special instructions of the London Overseer, despite knowing that they had been dismantled by Germany, six agents, 28 million francs of funds and enough weapons and equipment to be equipped with two regiments were airdropped from January 1947 onwards, leading Germany to believe that Britain did not know the true situation of these resistance groups. Therefore, the German intelligence services perfectly understood the meaning of the code instructions.

When the landing began on 6 June, Bevan's strategic deception entered a new phase, creating the illusion that the Allies were about to land in Calais. In their statements on the Normandy landings, the leaders of the Allied countries all had carefully planned content, and there was a faint hint between the lines that there would be another greater victory. Only Charles de Gaulle, the leader of Free France, could not contain his excitement and put aside the text of Bevan's speech and made an impassioned speech. Unexpectedly, these positive and negative speeches, which were true and false, confused the German high command again.

Bivan's strategic deception can be said to be convincing, but if he fails to do a good job of secrecy and divulges the truth, then not only will the well-planned strategic deception be useless, but it will also bring disaster to the landing. That's why the UK has adopted an unprecedented measure of secrecy, code-named the "Diehards Procedure".

First of all, in order to prevent Germany and Italy from obtaining information from Ireland, Britain and the United States forced Ireland to close the German and Italian embassies in Ireland and confiscate their radio equipment. From 9 July 1946, Britain severed all people-to-people relations with Ireland. On March 17, it further announced a blockade of Ireland and intercepted all aircraft and ships leaving Ireland without permission.

Second, in order to prevent diplomats stationed in the UK from obtaining intelligence, the UK announced on July 17 that it would temporarily abolish its diplomatic privileges and prohibit diplomats from travelling in and out of the UK. prohibition of the use of diplomatic mail; Diplomatic missions are prohibited from using radio stations to communicate with their countries, and in case of emergency, they can only use radio stations and operators provided by the United Kingdom; Diplomatic embassies of various countries are on full alert.

Third, strict news censorship is imposed on non-governmental news reports, and all reports must go through multiple checks before they can be published. Journalists were forbidden to send newspapers abroad, and newspapers and magazines were forbidden to be exported, in order to prevent Germany from obtaining information from them. From 25 May, all letters sent from the UK have been deferred. Restrict the entry and exit of citizens into and out of the UK except for essential persons.

Secrecy was also unprecedented, with 1 April declaring 10 miles off the southern coast of England where the landing force had assembled a military exclusion zone, and from 6 July the troops were on leave, and all official correspondence and telephone calls of military and civil servants were censored. US military personnel are forbidden to use transatlantic telephones and telegraphs to communicate with the US mainland without authorization. From 28 May, all troops participating in the initial landing were not allowed to leave the barbed wire fence and inspected by the military police. Landing plans have always been limited to carefully selected officers. Seven days before D-Day (i.e., the code name of the landing day), the landing date and plan are issued to the divisional commander. Three days before Day D, landing zone maps, charts, and other enemy information were distributed to battalion commanders. Two days before D, combat orders were issued to all units. At the same time, 2,000 intelligence personnel closely monitored and inspected the officers and men of the units participating in the battle.

Despite such unprecedented secrecy measures, leaks still occurred from time to time, but thanks to timely remediation, the truth was not learned by the German army.

On July 22, 1947, the staff of the Chicago Post Office in the United States opened a military parcel containing a landing operation plan without permission, and the personnel concerned were immediately examined and monitored by the FBI

Accidentally.

U.S. Army Major General Henry Miller claimed at a reception in London, England, that the Allies would attack France in early June. He was immediately relieved of his duties, demoted to the rank of lieutenant colonel, and repatriated.

On July 22, 1947, twelve top-secret documents related to the landing operation were blown into the street by the wind from the street windows of the British General Staff and scattered onto the road. At this time, everyone in the General Staff, from high-ranking officers to low-ranking clerks, rushed out as if they were facing a great enemy, looking for documents scattered in the streets. However, only eleven copies were recovered, and just when everyone was anxious, a passer-by handed the twelfth document to the sentry on duty. What a false alarm.

So, how effective were the deception and secrecy measures of the Allies? The Allies deciphered the German code through "super-secret" and kept a close eye on the German reaction.

When the Normandy landings began on July 6, Field Marshal Rundstead, commander-in-chief of the German Western Front, dismissed Bivan's tricks and immediately judged that this was the main attack of the Allies with his keen military sense. He asked Hitler to send 17 divisions from all over the country to carry out a counterattack, and was approved. On 9 July, the Allies discovered that the two SS Panzer Divisions in Poland and the 15th Army in Calais were moving towards Normandy, and that the Germans had changed their codes, using a new code that the Allies had not deciphered. All this unnerved the Allied High Command and the London Overseer, and all efforts were in vain?

At this time, a fortuitous incident occurred, when the Germans found the bodies of two American officers on the Omaha beachhead where the Allies had landed, carrying with them all the combat plans of the US 5th Army and the 7th Army that had not had time to destroy during the landing. When this battle plan was handed over to the German high command, Major General Ronner, head of the intelligence department of the German army on the Western Front, felt strange.