I know for a fact that Allied forces were slightly inferior to German forces on some points. I know that the Ardennes was ill-protected on the French side. The defenses were poorly constructed, and the battle's plans were not properly executed.

Then I found this source where German military planners claimed that:

  • an invasion via the Ardennes had no chances of success because they had to sleep at night.

  • Germany mass-produced amphetamines for its armed forces.

  • Germans were actually surprised that their plan did work.

So, my questions are the following.

  1. What are the objective reasons for the devastating defeat the Allies suffered in the Battle of France?

  2. Was the French high command actually that bad?

  3. Or did these drugs play a major role in the French defeat?

  • 7
    Whole books have been written about this. You can start with the phrase "Generals always fight the last war" and follow up with learning about blitzkrieg. Then look into the political difficulties that hampered Britain, France and the Low Countries from working together.
    – user15620
    Commented Oct 5, 2017 at 17:09
  • 1
    This question is okay. Unlike most others of its type, it actually identifies a specific concern.
    – Tom Au
    Commented Oct 5, 2017 at 20:03

3 Answers 3


The main reason was that the allies were prepared to fight WW1 all over again. The Germans had very different ideas. The allies were ready to fight a static trench war in Belgium. Problem was that Belgium declared neutrality in 1936.

That created huge problems for the allied planners. Allied officers were not allowed to coordinate with Belgium before hostilities broke out. Then they discovered that the positions they were supposed to occupy weren't ready.

Even worse: the Germans also violated Dutch neutrality, which caused the allies to (try) to set up defenses - for which they weren't prepared - much further north into Holland. French troops were moved to Breda (North Brabant) but never even got there.

General Gamelin set up his HQ in Château de Vincennes. FAR behind the front. In Paris itself, actually. With almost no communication with the outside world: only a few (I thought one) telephone lines. Allied communications were based on telephones with cables. The Germans used radios extensively. Allied planning was hopelessly behind actual events. Every time the French set up a defensive line, it was already bypassed by German troops.

The Germans initially planned to use the von Schlieffen plan again. Until a German plane made on 10 Jan 40 an emergency landing in Belgium with their plans. Von Manstein made a different plan, Fall Gelb (plan Yellow) which was adapted by Hitler (he presented it as his own idea) very much against the will of von Mansteins superiors.

The allies were about as strong as the German army, perhaps a few divisions stronger. A big difference was combat experience. The German had it (Polish campaign), the allies not. They had also more and better tanks, but they employed them wrongly. The Germans concentrated their armored forces into strong units with which they spearheaded their attack. The allies spread them all over they army. German air power was vastly superior to allied air power, both in machines, experience (Spanish civil war, Poland) and tactics.

German tanks, by the way, weren't very good. Later on in the war much better tanks were developed. The PzKw I and II were too small, too lightly armored and armed. But they were employed in the right way, had radios (most allied tanks didn't) and that made all the difference.

Gamelin was very old (73), not very popular with the troops (he rarely visited them) and his political masters. Premier Reynaud tried to sack him many times. Eventually he was replaced by Weygand who was even older... Replacing your commanders during a battle you are already loosing is never a good idea.

The only general that stands out positive during this campaign is Lord Gort. He made sure the BEF retreated to Dunkirk and wasn't wasted in spoiling attacks to hold the line.

The Germans did use a lot of amphetamines to get the most out of their troops, but with mixed results. Yes, they could fight much longer. But once the stuff stopped working, you had to rest. There and then. And very long, several days at least to recover. It was very useful on limited targets, such as the capture of Fort Eben Emael. Giving it like Oreos to advancing infantry units wasn't a good idea. Fortunately (for the Germans) the French high command was bad enough so it didn't matter much.

The Germans weren't surprised that their plan did work, they were far more surprised it worked so well. For example, Von Rundstedt's infamous Halt order at Dunkirk showed the German high command got cold feet. He was sure the allies had prepared a counter offensive or a big trap.

  • 1
    Nice answer - you are getting very close here I think. Tactical doctrine at the unit level and between services was the great strength of the Germans. The Pz I and II should be regarded as scout cars rather than tanks, (armour barely sufficient to stop small arms bullets)which gives the French alone nearly three times as many tanks as the Germans; but without radios, and with one or even two fewer men in each tank, they were individually much less efficient on the battle field. Commented Oct 6, 2017 at 10:09
  • The average French, and especially British, unit was better trained, better equipped, and arguably even better led, than the average German unit. It had far more motorized capability than any except the elite divisions on the other side. But the Panzer and Panzer Grenadier (motorized) units were far superior in training, leadership, and doctrine to anything on the Allied side in 1940. Commented Oct 6, 2017 at 10:14
  • 1
    I don't think Lord Got was particularly outstanding. Many generals in his situation would have fled all the same (fleeing was justified). He didn't even warned French and Belgium's troops before fleeing. If I remember well, Belgium surrendered sooner because of that. But this move is typical of British strategy, they are really machiavellians. In some way that's impressive. But I have always despised the easiness and the scale where allies and natives were sacrificied for the glory of the British Empire. Plausible deniability is such a wonderful tool.
    – xrorox
    Commented Oct 6, 2017 at 15:52
  • 1
    I am not disagreeing with the content of this particular answer, but it bothers me that so many answers on so many of the stack exchange sites just, or mostly, refer to wikipedia. 10 references in this answer. No, we don't all have access to the best source material, but wikipedia does have some serious flaws and seeing it used so uncritically, automatically and unquestioningly concerns me.
    – user18963
    Commented Jun 13, 2018 at 13:31
  • 1
    @mickeyf No problem at all. Show me where my references are wrong, and I'm more than happy to correct them. If you can't, why bring up the subject?
    – Jos
    Commented Jun 13, 2018 at 14:09

Allied forces where driven back not only in the Ardennes, but also along the whole Belgian front. Hence, even with a poor strategy germans would have won the battle.

Most important reason was the lack of reserves in the french side, while germans had two complete armies behind their main thrust, allies have none. So any opening would be impossible to close in a short span of time. Many french forces where in the Maginot line at the beginning of the battle, but the battle was fought in the north.

Second; Lack of coordination between Allies, not only british and french. Belgium and Holland did not coordinate their forces with them. Once their countries were occupied they left the battle. If you sum forces from all these countries, they were almost equal in number compared to german forces.

Third; Lack of experience in the allied side, germans made a lot of changes after Poland campaign, but allies did not have experience, so their first battle in world war II was France. It is noticeable that while more advanced the battle of France better was the performance of allied forces.

Fouth; Brute numbers, at the end of the campaign germans had 155 divisions, Allies never had more than 135 divisions at the same time.

Fifth; Geography, western front is actually small, so a tactical defeat easily turns into a major defeat in few days. Russians had the same problems at the beginning of Barbarossa, but the country is so huge that they had space to give in. Actually, the distance from the frontier to Calais is similar to the distance between eastern frontier and Minsk in Russia (of from Minsk to Smolensk, or Smolensk to Moscow).

Battle of France was lost in six days, because the gap by that day was so big that it was impossible to close without reserves, removing any chance of a organized retreat.

  • 1
    A supporting reference: en.wikipedia.org/wiki/…
    – AllInOne
    Commented Oct 5, 2017 at 19:47
  • Do you 135 number exclude french fortress troops protecting Maginot Line ?
    – xrorox
    Commented Oct 6, 2017 at 15:04
  • @xrorox, included Maginot line forces.
    – Santiago
    Commented Oct 6, 2017 at 16:46

Just adding that French politics at the time were hardly helpful. There is the situation with La Cagoule a French fascist-leaning group that plotted to overthrow the French government. They had been caught and then released. Which really seems a bad idea when being invaded. https://en.wikipedia.org/wiki/La_Cagoule There was the odd political beliefs of Pétain and exactly how was he able to get the powers of a dictator. Here is a strange historical tidbit the https://en.wikipedia.org/wiki/Riom_Trial which was the Vichy government attempt to lay blame which backfired.

  • 1
    Welcome to History:SE, user32218! This post is quite short and only alluding to "bad ideas" and "a trial", both essentially just in lonks. Could you elaborate a bit on that and try to summarise and explain what happened and why that was a "bad idea"? Was that French fascist group a significant factor? Commented Jun 13, 2018 at 1:47

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