What strategic military construction did France undertake before World War II?

Before World War II, France undertook the construction of the Maginot Line as a strategic military defense system along its eastern border, primarily against a potential German invasion. This extensive fortification was built between the two World Wars and consisted of a series of fortresses, bunkers, and defensive structures designed to deter and withstand aggression, notably from Germany.

The Maginot Line reflected France's experience in World War I, where trench warfare demonstrated the need for strong defensive positions. France hoped that this line would allow them to better prepare for a repeat of such conflict and provide a sense of security. However, the line's effectiveness was compromised by Germany's strategy of bypassing it in 1940 during their invasion, illustrating the limitations of relying solely on fixed defenses without accompanying mobile warfare strategies.

In contrast, the other choices represent different historical military constructions: the Siegfried Line was Germany's counter-fortification, the Berlin Wall was a Cold War artifact, and the Atlantic Wall was built by Nazi Germany during World War II to defend against an Allied invasion. Each of these was relevant to different contexts and conflicts and did not serve the same purpose as the Maginot Line in the lead-up to World War II.