What are three major mistakes that were made in the construction and usage of the Maginot line?

Answer 1

The most significant mistake was that the line was not completed all the way to the English Channel or tied into the Belgian fortification network. Therefore the Germans were able to outflank it by invading through Belgium & Netherlands.

Once you start building an obstacle or fortification network, it is much less valuable if it is not completed. A great deal of money was spent by the French before the war on its construction. It seems wasted today, however if it had been completed then the Germans would have had a much more difficult time breeching this network, regardless of its use of divebombers, airborne/glider & panzer units. However, the network still required the French to maintain mobile forces to support the Maginot Line. These forces were overwhelmed at the western flank during the invasion.

The failure to complete the line is linked directly to the French military-political relationship with Belgium. The Belgians wanted to remain neutral but friendly with France. The French could not link their Maginot Line to the Belgian fortifications because of official Belgian neutrality. The French could not build the line to the sea behind the Belgians because of the informal military cooperation with the Belgians.

This shortsighted foreign policy blunder of Belgium allowed/forced the Germans to invade Belgium to avoid the Maginot Line.

Ironically, now having learned their lesson, Belgium is the location of the current Headquaters home to the world's currently most important military alliance, NATO.