The French Maginot Line (in use from 1935 to 1940) from World War II has come to stand as one of the great symbols of shortsightedness, Myopic Architecture, stupidity, ostrich-like response to threat, and just general fail. The French built the most advanced system of fortifications that the world had ever seen — and, in the popular imagination, just sat there in their fortifications while the Germans did a huge Dungeon Bypass by invading indirectly through an area where the line was incomplete.
The above story is, however, an extremely pervasive case of Artistic License History. In real fact, the goals of the Maginot Line upon its construction (1930) were this:
- Force the Germans not to attack there. This would hopefully lead to Germany invading Belgium in order to actually get at France, which would bring Belgium into the war on France's side. In the long term this would enable an invasion of Germany through the flatter and more favourable terrain of northern Belgium, the terrain and infrastructure of the Franco-German border (hilly and poor, respectively) being unsuited to offensive incursions into Germany anyway. The French very much preferred to fight the Germans in Belgium and Germany, and not France.
- Free up soldiers for the real fight up in Belgium. France really needed this: she had lost so many younger men to World War I and The Spanish Flu that there was gaping hole in the manpower pool where the forty-something year-old men were supposed to be.note Moreover another hole in the manpower pool was looming, the number of men turning 18 in the years 1932-7 being just half that of previous and subsequent years. Germany, Britain, and Italy also had these gaps but France's were (proportionally) bigger. Thus, she badly needed economy of manpower.
- Prop up domestic manufacturing at a time of low demand.
So the French expected that the Germans would invade France in an attempt to defeat her and so break the Franco-British blockade which would be crippling the German economy even worse than in World War I, and that they would do so by bypassing the Maginot Line through Belgium. The Germans knew this too, they both knew that the other side knew, and this is what the Germans did, to nobody's surprise. So what happened? Why did the French lose so badly?
Well, for the purpose of this analysis, you can divide Belgium into two regions:
- The northern plains, where the majority of the population lives. This is excellent tank country and has two major double-tracked railway lines, several single-tracked lines, and very good roads an area that most, though not all, of Germany's forces could be supplied through without too much trouble. In World War I this is where the August 1914 German offensive had entered France from.
- The Ardennes Forest, south of the northern plains and north of the Maginot Line. The Ardennes isn't just a forest: it's a rugged, hilly, wooded country with a couple of single-tracked railway lines and a few bad roads. This is not good tank country, and attacking through there with just half of Germany's forces would require every motor vehicle in Germany to have the slightest chance of keeping the advance supplied. In World War I the French attempted to invade Germany through here (to cut off the German force that they anticipated would soon invade northern Belgium) and failed miserably.
The French high command expected that the Germans would attack through the northern Belgian plains, because this is the non-insane plan - and the one that worked Last Time. They were also aware that the Germans were really good at tank-supported direct artillery attacks upon tactical strongpoints. Given just how strong the French artillery force was, to overcome it they would need the advantage of relatively flat terrain - so they'd have to deploy their tanks in the north.
There was a chance the Germans might count on the French assuming this and so deploy their tank forces in the Ardennes instead, but the temporary surprise this maneuver might cause would be more than offset by the difficulty of breaking through the artillery-heavy French lines and the sheer logistical impossibility of sustaining such an offensive. Sustaining a major offensive through the Ardennes by the usual combination of rail and horse transport wasn't possible by a long shot. The German Army's horrific logistic troubles supplying troops through the region in World War One, even given lower average demand for ammunition relative to post-1916 military forces, was proof enough of that. note
So what did the Germans do in the Battle of France? They launched a feint attack up in the northern plains of Belgium and Holland to distract the French and play to their expectations, and in the meantime they secretly sent their main force through the Ardennes. French mechanized forces established a weak series of outposts across both areas, the bulk of Franco-British infantry forces were moved by rail to the northern plains, and a weak follow-on infantry force was later moved to the Ardennes. So when the German forces actually encountered the French mechanized forces in the Ardennes, they outnumbered them by something like 20:1. And once they broke through them, the French infantry force in the area was also outnumbered by 10:1. And once they broke through them, there were no more prepared defensive outposts and the only troops in their way were ones hastily railed in to stop them. Who were also outnumbered.
The German mobile forces trapped about half the entire Allied forces in Belgium, where they could not expect to receive much ammunition from the depots in France for at least several days. The Germans had no intention of letting them receive it, and moved to separate the Allied troops from the ports and to force individual pockets of troops to run out of ammo and surrender. The Allies' only hope at that point would have been to use some reserves to counterattack the German spearhead, but they had sent too much of their force into northern Belgium. The rail infrastructure did not allow them to muster a sufficiently large force in the little time they had, not least because much of their force had moved away from railway stations to occupy key positions in the defense of the rivers.
While few Allied commanders were actually surprised or fazed by this development, the French army as an institution (with several thousand managers [commanders] who needed advanced notice to work out and execute plans if you didn't want utter chaos) was unable to react in a timely and sufficiently organised fashion. So the Germans managed to cut the supply lines to the best French and British units, and defeat them dramatically and quickly.
One curious fact was that the Germans originally planned to do exactly what the French expected: attack through northern Belgium. However, neither Hitler nor any of the generals was enthusiastic about this plan; in addition, at one point, the Belgians captured a German officer who had a copy of a draft of this plan. Legendary German General Erich von Manstein (who understood logistics), with the help of the somewhat-back-stabby Blood Knight Heinz Guderian (who did not, but inspired Manstein to greater boldness in the planning), came up with this Ardennes attack plan. Chief of the German General Staff General Halder disliked this idea at first, but Hitler had independently suggested something similar early on and Halder was partly browbeaten and partly personally overawed by Hitler into accepting the Ardennes plan over the northern plains plan.
Most of the other German generals thought this was nuts, not because of the constricted supply lines this would entail because the logistics services were never consulted or even mentioned when planning campaigns/operations - they were just expected to fulfill any and all demands placed upon them.note Rather, they wanted to fight the French on the open plains and didn't think the hills of the Ardennes were good for this because they would give the French a defensive advantage. Manstein and Guderian insisted that most of the fighting would in fact take place on the plains and not in the hills (though they'd have to go through the hills first and there'd be a fair bit of fighting there first), but their contemporaries thought this was overly optimistic and potentially disastrous.
The Ardennes plan was indeed very risky; if the Allies had clued up earlier about it, the Germans wouldn't have just suffered a terrible defeat and gone on to lose the war, but they would have looked incredibly stupid. People would be asking today how could the Germans have been so stupid to think that they could successfully launch a major mechanized attack through such terrible terrain and bad roads. And in fact, the German attack force's movement through the Ardennes was a logistical nightmare; it caused the largest traffic jam the world had ever seen to that date, and for a few days the Germans would have been sitting ducks to Allied air attacks. General Halder chose it because, in spite of the risk, it offered a chance of victory, whereas they knew that the northern Belgian attack didn't. (It's also worth mentioning that Halder disagreed with the war against France and Britain, had been plotting against Hitler, and would have probably preferred a quick loss against the Allies than a protracted losing war against them.)
But, in an excellent demonstration of the old maxim "The winning army is the one that makes the fewest mistakes," the Allies didn't figure it out in time. The historical record shows that they received many clues of the true German plan, yet either they failed to connect the dots or they dismissed them as misinformation. For example, in the heat of the first couple of days, the French Generalissimo Gamelin was told about a German force moving through in the Ardennes, and he concluded that this was a secondary attack meant to distract him from the main attack up north. The opposite from what was happening! (Which, to be fair, was the original German plan)
A complicating factor that affected the French and British strategy was the loss of the Belgian fortress of Eben Emael. If attacking across the Franco-German border would have been extraordinarily difficult, a direct assault on Eben Emael was insane. It was, at the time, the toughest nut in the world to crack, and its position was designed to further restrict German movement, designed to serve as an anchor for the planned Franco-British defensive position. The only problem was that no one considered the possibility that anyone would be crazy enough to try and land a small force of glider troops on top of the fortress. Which, of course, the Germans did, which allowed them to capture the fortress, forcing the British and French to scramble to reform a new defensive line. These glider troops (they didn't use parachutes) used an honest-to-God secret weapon, the shaped charge explosive, to blow up the artillery turrets. The action was so quick and swift that only a few men died on both sides.
Soon after the breakthrough, the entire British Expeditionary Force and the majority of the French Army were thus trapped near the French town of Dunkirk. With nowhere else to run, the British gathered everything that could float and rescued the near-entirety of the BEF and a good number of French troops. The Germans, meanwhile, were halted as Luftwaffe Commander-in-Chief Göring persuaded Hitler that his planes could annihilate the remaining Allied forces. This did not happen due to poor weather making aerial attacks difficult, and since then, the German Army began to distrust the Luftwaffe. Despite this, the Allied defeat was total. Britain was ejected from the continent and, having left nearly all their equipment and heavy arms at Dunkirk, unable to redeploy their forces, giving the Germans free reign to maneuver in Western Europe. Less than ten days later, General Erwin Rommel and his 7th Panzer Division, who moved so quickly even Berlin lost track of them during the campaign, sent a message to army headquarters as they stood overlooking the English Channel: "Am at coast." The Wehrmacht then turned south to capture Paris, now an open city, before they were finally halted on June 22, when an armistice was signed between Germany and France.
Alert readers will notice that we haven't said a word about the Maginot Line for many paragraphs at this point. So let's get back to that. Was the Maginot Line a stupid idea that completely failed? No, it wasn't; it was a reasonable idea that did exactly what it was intended to do (force the Germans to attack through Belgium; free up soldiers to counter that attack). Was it a good idea? That is a much harder question. It is possible that the French would have done better if they'd spent more of their resources on other things like better mechanized forcesnote , better intelligence analysis, better training, etc.; but this doesn't mean necessarily that they shouldn't have built a Maginot Line, but rather that they could have spent less on itnote , and more on other things. However, it's important to remember that, historically, even with the strategic choices they made the Allies had serious chances of winning the Battle of France in the early days, and of not losing so badly even after the initial surprise. They also arguably could have won the war if they'd invaded Germany in 1939 instead of waiting for the Germans to attack.
So the Maginot Line played an important role in the Fall of France, but not a dominant one.
A final important fact is that the French high command was warned of the dangers posed by Ardennes assault since 1938. In May-June 1938, General André-Gaston Prételat staged a map exercise to determine what would happen if the Germans decide to use tanks to attack through the Ardennes and how long would it take for the Germans to go through the forest and reach the Meuse. He concluded that it would take 60 hours, which is only 3 hours more that what Germany actually pulled off later in 1940. The French high command, especially Gamelin, instead chose to accuse the general of pessimism, bury the exercise result to prevent lower rank panic, and keep insisting that it would take much longer than that so they can easily ignore putting defense in place and count on organizing counterattack instead. You could imagine how different the war could turn out if Prételat's warning was taken seriously.
Fun historical fact: you'd think that, after the Allies were defeated catastrophically by a surprise German attack through the Ardennes, they'd never fall for the same trick again, right? Well, that's only half right: in the Battle of the Bulge, four and a half years later, the Germans managed to trick the Americans and launch a major surprise attack through the Ardennes (under the cover of fog and bad weather which grounded their air-forces), which the Americans considered a quiet region of the front and thus had sent weakened divisions there to recover. However, the Americans were better-armed and more numerous relative to their attackers than the French had been four years earlier and put up a much better fight. More importantly, this Allied commander (General Patton) correctly judged that this would be the main thrust of their offensive and rushed in so many troops (chiefly the US's Third Army) that the Allies soon had the attacking Germans outnumbered and out-gunned. Once their offensive had effectively been halted the Germans quickly withdrew as their positions were exposed and Hitler wanted their mobile formations dispatched to Hungary as quickly as possible so they could try to relieve the Siege of Budapest in Unternehmen Konrad.
Also note: invading through the Ardennes had already been used by the Germans in World War I and went pretty badly for both sides, with the German invasion force running out of food and horses at a ridiculous rate due to the area's poor infrastructure (and the French demolition of said infrastructure as they retreated). Further note: invading through the Ardennes was also used in the Franco-Prussian War of 1870; as in 1940, the Prussians managed to achieve effective surprise against the sluggish French and inflicted a devastating defeat.