In the evening of June 5th, the BBC broadcast a long list of messages to French Resistance workers. Contrary to an idée reçue, the famous line from Verlaine (“Bercent mon cœur d’une langueur monotone”) did not constitute the general message announcing the start of the Landings, but was just one of many. Each of these had a specific meaning: “Il fait chaud à Suez” triggered the start of the guerrilla war against the enemy; “Les dés sont sur le tapis” was the signal to implement the “Green” plan (the sabotaging of railway lines), while “Ne faites pas de plaisanteries” was the “Purple” plan (the sabotaging of the telecommunications networks).
Throughout the night, Normandy’s resistance groups busily cut telephone lines, felled trees to block roads ‑ which they also scattered with mines and devices to puncture tyres ‑, reversed road signs and blew up railway lines. These frequently daring acts, which continued over the following days and were mirrored in every region of France, helped to reduce the enemy’s ability to react. Combined with the action of Allied aviation, the constant harrying of the Germans by the FFI on the roads and railways considerably delayed the arrival of reinforcements at the front in Normandy.
The Resistance also proved invaluable in guiding the advancing Allied troops. Reconnaissance missions behind enemy lines provided priceless information, not least the Helmsman mission, which played a vital role in preparations for Operation “Cobra” and the decisive American break-out at the end of July.