 When the British Expeditionary Force landed in France in September 1939, they and the French reinforced and extended the Maginot line to the sea in a flurry of construction from 1939–1940 accompanied by general improvements all along the line.The final line was strongest around the industrial regions of Metz, Lauter and Alsace, while other areas were in comparison only weakly guarded.In contrast, the propaganda about the line made it appear far greater a construction than it was; illustrations showed multiple storeys of interwoven passages and even underground railyards and cinemas.