If they had constructed it right across the Belgian border Mr Hitler would not have had such an easy ride
They could not build it across the
border with Belgium because the countries had signed an alliance in 1920, by which the French army would operate in Belgium if the German forces invaded. When Belgium abrogated the treaty in 1936 and declared neutrality, the Maginot Line was quickly extended along the Franco-Belgian border, but not to the standard of the rest of the Line. There was a final flurry of construction in 1939-40 with 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.