Following the Battle of France, the German 15th Army established its headquarters at Tourcoing. The 15th Army was deployed in Normandy and the Netherlands. The headquarters consisted of thirteen concrete blockhouses. These protected the occupiers against air strikes and chemical weapons. German soldiers with small arms and machine guns controlled physical access to the bunkers. During Allied planning for Operation Overlord, the actual date of D-Day needed to be kept secret, but the Allies depended on cooperation with the French Resistance. On 1 June 1944, a message was broadcast over Radio London to inform the Resistance that the invasion could be expected within 2 weeks. The first message consisted of the first three lines of Paul Verlaine's poem Chanson d'automne: Les sanglots longs des violons d'automne. On 5 June, at 9:15 pm, Radio London broadcast a second message: the next three lines from the same poem. Blessent mon coeur d'une longeur monotone, or "Wound my heart with a monotonous languor", meant that the invasion was to begin within 48 hours. The Resistance was supposed to increase its efforts against German supply lines, especially railroads, in anticipation of D-Day. At Tourcoing on 5 June, the 15thArmy Headquarters intercepted the message. It was 23:45.
The museum today
The largest of the thirteen blockhouses, a Type SK1 Bunker number 381, was converted to a museum. It is dedicated to the installations of the Nazi occupation of France and how those installations worked. The rooms most important to the bunker's wartime function — the generators, ventilators, telephone exchange and translation department, as well as the general's office, kitchen and guard post, are open for public view and are restored to wartime appearance. Other exhibits include methods used by the Gestapo to detect and locate radio transmitters used by the Resistance and a room dedicated to the landings in Normandy. For 2013–2014, the museum has an exhibition dedicated to the commandos who were the first French soldiers to land as part of the liberating force. The museum's stated objective is "to fight for remembrance and against all forms of revisionism."
