It is named after the message sent by the BBC's Radio Londres at 9:15 pm on June 5, 1944 announcing the imminent invasion of Normandy.
German soldiers with small arms and machine guns controlled physical access to the bunkers.
The Resistance was supposed to increase its efforts against German supply lines, especially railroads, in anticipation of D-Day.
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.