After advancing through Normandy in the summer of 1944, British troops began to pursue retreating German units into Belgium. The troops, whose objective was the capture of Lille and then Brussels, found themselves in the centre of the operation, supported by the Canadian and Polish forces on the left wing and the American forces on the right. The route followed by them was Amiens-Antwerp. The liberation of the mining basin and the two main towns of the Nord-Pas-de-Calais region, Arras and Lille, fell to them.
Their progress was rapid, as the British troops were pursuing a routed army. Fighting was very limited: Amiens was recaptured on 31 August, Arras and Douai on 1 September, Lens on 2 September, Lille on 3 September and finally Bethune on 4 September.
The British forces chose to bypass the Lille conurbation, that was fought over by the French Forces of the Interior (FFI) and the remaining occupying troops. They moved on to Brussels, which was liberated on the same day as Lille. In just five days, the British troops liberated the territory of the Basin and the cities of Amiens, Arras, Bethune, Lens and Lille.