​​The resistance fighters of the French Forces of the Interior (FFI) played an important role during the liberation of the French territory. From the time of the Normandy landings onwards, they distinguished themselves by carrying out the various actions decreed by the Allies, that aimed to paralyse the communication routes used by the German forces. On 27 August 1944, the FFI insurrection began: they gathered in the centres provided for this purpose and brought out the weapons that had been either hidden since 1940 or parachuted in by the Allies. The FFI played a role in the liberation of Lille and Tourcoing, which were bypassed by British troops in pursuit of the retreating German soldiers.

On 30 August 1944, the departure of the occupying forces began.

​All over the region, FFI groups gathered to take the last occupying troops prisoner, to guide the Allies and to ensure the surveillance of the infrastructures essential to the liberation. On 1 September, a number of local Resistance groups met in Fives and jointly prepared what needed to be done for the liberation of Lille, the capital of French Flanders. The next day, they succeeded in liberating the citadel, which allowed them to seize grenades, rifles and some heavy machine guns. As the Germans continued to withdraw, the resistance groups were ordered to take possession of the former headquarters of the German occupiers: first the town hall, then the chamber of commerce — the seat of the Kommandantur.

Despite the progress of the Resistance fighters, several tanks were still stationed in the town centre. These were evacuated by the FFI. In the evening of 2 September Lille was almost entirely liberated. The next day, with the help of British troops, the last Germans were taken prisoner and by 17:00pm French flags were flying from all public buildings in the city.

The actions carried out by the FFI were on their own initiative and despite the weakness of their weapons. The Resistance paid a high price for the liberation of the region: a hundred FFI were killed during the liberation of Lille.

​Today, a plaque at Place Martin Luther-King commemorates the actions of the FFI during the liberation of Lille. It bears the words "Les Forces Françaises de l'Intérieur, les prisonniers, les combattants à leurs morts", in English "The French Forces of the Interior, the prisoners, the fighters to their death".​