The Canadian Divisions had been holding Vimy Ridge for several months when they received the order to advance on Lens. Between 15th and 25th August, the Canadians fought many street battles in the surrounding towns but, in spite of their efforts, Lens remained in German hands until the invaders withdrew in October 1918, leaving behind them a town in ruins.
The Germans occupied the region early in the war and by the autumn of 1914 they held most of the Pas-de-Calais coal basin, except for the mines in Béthune and Bruay which remained under French authority. In 1917, under heavy pressure from the British Army on Vimy Ridge, the Germans evacuated the civilian population of the town and proceeded to sabotage the coal-producing facilities by flooding the mineshafts and carrying off the machinery to Germany.
In 1918 the floor of the town, already very unstable because of collapsing mineshafts, was severely cratered to a depth of 4 or 5 metres by the shelling. Works to clear away the rubble and level off the ground, which were necessary for any subsequent reconstruction, started in February 1919 and lasted until the end of 1921.
Lens's public buildings were rebuilt in two styles. The buildings around Jean Jaurès Square, such as Saint-Léger Church and the Town Hall (destroyed again in 1944), were rebuilt in their pre-war style and the architect Louis-Marie Cordonnier gave Lens University an appearance which reflected regional traditions.
However Art Deco became the most influential style of the new Lens. The railway station, designed by Urbain Cassan in 1926, was given the shape of a 1920s steam locomotive with a clock tower for its funnel and exaggerated arches for its wheels. The building comprises 11 separate sections made in reinforced concrete and seated on hydraulic lifting jacks to compensate for any subsidence that may be caused by collapsing mineshafts. Inside the building, cubist-inspired mosaics by August Labouret depict themes related to mining and industry.