Where would the real planned invasion of France take place?

The Manstein Plan is one of the names used to describe the war plan of the German Army during the Battle of France in 1940. The original invasion plan was an awkward compromise devised by General Franz Halder, the chief of Oberkommando des Heeres staff (OKH, Army High Command) and satisfied no one. Documents with details of the plan fell into Belgian hands during the Mechelen incident of 10 January 1940 and the plan was revised several times, each giving more emphasis to an attack by Army Group A through the Ardennes, which progressively reduced the offensive by Army Group B through the Low Countries to a diversion