Cormeilles-en-Parisis - quiz moment!

Answers b) and c)

Please note that Radar only became operational during the 2nd World War.

To avoid the increasingly frequent and deadly bombardments of Paris, the French army launched a project in 1918 to create a replica of Paris, notably at Cormeilles-en-Parisis.  In this way, the Germans would be able to see a fake Paris from the air. By turning off all the lights in Paris and lighting up all those in the Saint-Germain-en-Laye forest, the bombers would have attacked an unoccupied area rather than the capital. The project included the construction of fake stations and avenues. 

Below is an English plan of the faux Paris project, with the sham railways dotted in white.

It was even planned that rolling trays loaded with lamps would be pulled by horses to simulate trains entering and leaving stations! Development of the project came to a halt with the end of the war, and the idea of the false Paris was never put into practice.

Pictured below is the Cormeilles-en-Parisis fort, built to protect Paris from attack. It could accommodate up to 1,200 men. Ile-de-France is rich in military relics from the First and Second World Wars.