French Underground during World War II, Communication and Codes

French Underground During World War II, Communication and Codes


By 1940, Nazi Germany had invaded several Eastern European nations and turned its attention to gaining control of Western Europe. With strategic planning reminiscent of World War I, the Nazis planned to forcefully invade France, Belgium, and Holland. However, when Marshal Henri-Philippe Petain rose to power in France, he negotiated an armistice with the Germans. On June 22, France was divided into two parts: the northern three-fifths and the Atlantic coast to be directly controlled by Nazi Germany, and the remaining parts of the south to be ruled by a French puppet government. The southern region was known as Vichy. The armistice also disbanded the French army, sending many French soldiers who could escape into exile in England. The settlement angered many French citizens, many of whom wished to continue the war against Germany.

As soon the occupation began, partisan groups arose to sabotage the Nazi government. These groups called themselves by many names (maquis, partisans, resistance, and freedom fighters) and the individual groups remained separate entities until the Allied invasion of France in 1944. These underground bands of French and foreign men and women who fought against the German occupation government became known collectively as the French Resistance.

The German secret police, the Gestapo, and intelligence agency, Abwehr, were powerful opponents to the resistance. In the early war period, German agents easily infiltrated resistance groups. In response, resistance groups developed codes, complex communications networks, and security structures to protect members and information.

Many of the earliest resistance groups were formed by political parties that the Nazi government had earlier banned. Communists and Socialists were persecuted under the Nazi regime. Partisan groups with political ties, such as the Socialist Comité d'Action Socialiste and the Communist Front National used their extensive media and member network to produce and distribute anti-Nazi propaganda. As resistance groups began to arm themselves and carry out acts of sabotage, the papers published coded messages that communicated instructions to members. During the course of the war, underground newspapers supplied information to over a million readers.

The resistance relied on coded messages to communicate with members and plan operations. Members were called by code names, and operational units had their own cryptonym or symbols. Underground newspaper published coded articles and drawings. Poetry was even used as a means of sending coded messages or identifying oneself as a member of a resistance group to other members.

The most famous, and perhaps ingenious security device of resistance groups was the use of a pyramid command structure. The pyramid structure ensured that no member of a partisan group even interacted or conducted operations with more than two other members of the organization. No records of membership were kept, and messages were sent only by word-of-mouth. Each resistance member knew one commanding member and one other partner member. Members kept strict confidentiality, and rarely met in groups larger than their operational units. This structure insured that enemy infiltrators and captured partisans could positively identify no more than two resistance operatives, leaving the rest of the organization unscathed. The strategy worked with some success, until Gestapo agents began to infiltrate the command echelons of various partisan groups.

The pyramid structure also added an operational advantage as well as security. Ambushes and assassinations of German officers were carried out by a group of three men. One man served as a decoy, the other carried the weapon and shot the victim at close range, while the third member took the weapon after the shooting and walked away from the scene. Often the actual assailants would remain at or near the scene until authorities arrived. As they possessed no weapons, they were cleared of suspicion. Because resistance members in most urban areas did not keep their own weapons as a security measure, weapons used in attacks were returned to their stockpile via courier, often a child, who would seldom arouse the suspicion of Gestapo agents.

French Resistance groups also developed an "under-ground railroad" system to smuggle downed Allied airmen back to Britain or the front lines. Using standardized coded messages, Allied servicemen were shuttled to various safe houses on route to their destination. Toward the end of the war, these same networks were used by Allied forces to send messages to various resistance groups throughout the countryside. Allied "Jedburg" teams, soldiers trained to aid the resistance, sabotage German supply lines, and unify the command of partisan groups, parachuted into France behind German lines. Individual Jedburg soldiers used the underground network to reach the towns or groups in which they were to operate. The two-way traffic of Allied servicemen in the "underground railroad" system facilitated communication not only with diverse resistance groups, but also with Allied command.

Jedburg groups also coordinated the procurement and allocation of radios to facilitate communication. While radios carried an increased risk of detection by occupation forces, they made mass communication over longer distance possible. Coded messages were transmitted nightly, both to Allied command and to various area partisans. Messages identified their recipients with a cryptonym and gave necessary instructions in coded messages. The codes were agreed upon in person, and then used in broadcasts to activate plans. When intercepted, the messages were easily identifiable as partisan transmissions, but their meanings were indecipherable. British radio, and the European underground radio, often rebroadcast Jedburg and other resistance messages. While this coding method was primitive, it required German forces to use spies instead of technology as primary means of breaking resistance group communications. Such missions were a costly drain on human intelligence resources, and carried a high level of risk.

In 1944, many of the largest French underground groups united to form the Conseil National de la resistance . The organization stockpiled weapons and worked with Allied intelligence operatives to prepare for the Allied invasion of France. During the D-Day invasion in June, 1944, the resistance cut German supply lines and aided Allied forces as they marched through France. Urban partisan members in Paris took to the streets in open warfare against the Germans, engaging forces until the liberation of Paris. With the Allied invasion, exiled members of the French Army, under the command of Charles de Gaulle, returned to France. Many resistance members then joined the army, fighting enemy forces throughout Europe.

Over the course of the war, the French Resistance scored key victories against the German occupations forces. Resistance members tracked and ferreted-out French collaborators, assassinated many ranking Nazi officials, tapped the phones of the Abwehr's Paris headquarters, and destroyed trains, convoys, and ships used by the German army. The resistance provided Allied forces with invaluable human intelligence resources and aided Allied troops who fell behind enemy lines. Resistance groups shielded political dissidents, refugees, and Jews escaping the Holocaust.

These numerous accomplishments carried a heavy price. German agents often infiltrated partisan groups, despite security precautions. When they captured a maquis, Gestapo agents employed torture as means of extracting the names of other resistance members. The Gestapo occasionally carried out bloody reprisals on innocent civilians after partisan sabotage operations. As many as 25,000 French men and women, members of the resistance and those suspected of aiding their cause, were sent to German concentration camps. Another 25,000 were executed in France by Gestapo agents, including the population of an entire Northern French village.



Aubrac, Lucie. Konrad Bieber and Betsy Wing (trans.). Outwitting the Gestapo. Lincoln: University of Nebraska Press, 1994.

Aubrac, Raymond, and Lucie Aubrac. The French Resistance: 1940–1944. Paris: Hazan Editeur, 1997.

Ottis, Sherri Greene. Silent Heroes: Downed Airmen and the French Underground. Lexington, KY: University of Kentucky Press, 2001.

Ousby, Ian. Occupation. Lanham, MD: Cooper Square Press, 2000.

Weitz, Margaret Collins. Sisters in the Resistance : How Women Fought to Free France, 1940–1945. New York: John Wiley & Sons., 1998.


France, Intelligence and Security
OSS (United States Office of Strategic Services

User Contributions:

Roland J. Bain
My uncle was an officer in the French army during WWII. After his escape from Dunkirk he was assigned to the "home guard" headquartered in Vichy. Resigning his commission he began working with the Resistance in Paris. His work included helping Allied airmen escape from France by helping them get to the south of France. Once he became wanted by the Gestapo it was time for him to escape, which he did over the Pyrenees (out of Itxassou). He re-joined the French army in North Africa.I want to learn if there is information available to connect him with a Resistance group in Paris. His name was Henri Dunat. He retired from the French Army as a general.

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