Europe’s attempts to appease Nazi leader Adolf Hitler, most notably at Munich in 1938, failed, as Nazi Germany swallowed up Austria and Czechoslovakia by 1939. Italy was on the march as well, invading Albania in April of 1939. The straw that broke the camel's back, however, was Germany's invasion of Poland on September 1 of that year. Two days later, France and Great Britain declared war on Germany, and World War II had begun in earnest.

Of course, as most people now know, the invasion of Poland was merely the preface to the Nazi blitzkrieg of most of Western Europe, which would include Denmark, Belgium, and France by the summer of 1940. The resistance put up by these countries is often portrayed as weak, and the narrative is that the British stood alone in 1940 against the Nazi onslaught, defending the British Isles during the Battle of Britain and preventing a potential German invasion.

Though the French would be decisively defeated soon after the Nazi invasion of Belgium and France in early 1940, they had not sat on their hands. As the power of Nazi Germany grew alarmingly during the 1930s, the French sought means to defend their territory against the rising menace of the Thousand Year Reich. As architects of the most punitive measures in the Treaty of Versailles following World War I, France was the most natural target for German retribution, so the Maginot Line, a series of interconnected strongpoints and fortifications running along much of France's eastern border, helped allay French fears of invasion.

The popular legend of the Maginot Line portrays the frontier defenses as a useless “white elephant” project that was prompted by a gross misapprehension of warfare's new realities in the mid-20th century and quickly overwhelmed by the forceful advance of the German blitzkrieg. English idiom today invokes this vision of the Maginot Line as a metaphor for any defensive measure strongly believed in but actually useless. Indeed, usages such as “Maginot Line mentality,” describing an overly defensive, reactive mindset, perpetuate the legend. As a French author and military liaison with the British, Andre Maurois, wrote about his disillusionment with the defensive line he originally enthusiastically supported: “We know now that the Maginot line-complex was a dangerous disease of the mind; but I publish this as it was written in January, 1940.”

In reality, the actual Maginot Line proved considerably more functional than memory has served. The true flaw in French military strategy during the opening days of World War II lay not in reliance on the Maginot fortifications but in the army's neglect to exploit the military opportunities the Line created. In other words, the border defense performed as envisioned, but the other military arms supported it insufficiently to halt the Germans. The French squandered the opportunity not because the Maginot Line existed but because they failed to utilize their own defensive plan properly.

This was what brought about the stasis along the Western Front near the end of 1939, a short period of time now referred to as the Phoney War, during which the Western Allies awaited some sort of action by the Nazis. Ultimately, the Allies had not expected the Germans would be able to move armored units through the Ardennes Forests, a heavily wooded region spanning parts of Belgium, France and the Netherlands. To their great surprise, the Germans had no trouble rolling across these lands in the span of weeks, and by invading France from the north, the Germans simply avoided the Maginot Line. The French surrendered in June 1940, and the British narrowly escaped disaster by transporting thousands of soldiers and equipment across the English Channel at Dunkirk.