France was invaded in 1940 and the 7th Panzer Division, commanded by Rommel, entered into Normandy. The objective being the capture of the Port of Cherbourg, the centre of Manche was spared and the German army occupied Saint-Lô, a strategic crossroads, on the night of 17 June 1940. During the occupation, the statue of the Norman dairywoman and the Havin statue, both made by Arthur Le Duc (fr) were sold and melted to make cannons, despite opposition from local politicians. In March 1943, the Germans decide to dig a tunnel under the rock. For the time being, no one is able to say what the usefulness of this tunnel would have been, though it was dug at the same time as the Agneaux Institute. Workers from the STO would be required until the beginning of the Battle of Normandy. Then, the underground, under construction, would house the sick of the Hôtel-Dieu located opposite and a part of the Saint-Lô population. A German soldier was shot in January 1944 and several people of Saint-Lô were arrested. The cinema, theatre and bars were closed, radios confiscated and the curfew was extended to 8pm.
During the Liberation, Saint-Lô suffered two attacks during the Battle of Normandy. The first was the bombardment of the city by the Americans during the night of 6–7 June 1944. The second was the fight for the liberation of Saint-Lô on 17 July, during the Battle of Saint-Lô. The city was this time bombed by the Germans who maintained their position to the south. Saint-Lô was almost totally destroyed (90-95% according to common estimates) by American bombing during a phase of the Battle of Normandy known as Operation Cobra, earning it the title of "The Capital of the Ruins" from Samuel Beckett. Saint-Lô was one of the key cities to the opening of the Falaise Gap, which ultimately allowed Allied forces to expel German forces from northern France.