Britain and France invade Germany after Germany invades Poland

Suppose Britain and France had put their whole armies on the French-German and invaded Germany after Germany invaded Poland. Would the Germans have been able to successfully fend off the invasion while conquering Poland at the same time?
 
It would have required Britain and France to mobilize earlier (before the invasion of Poland) and attack almost immediately after German attack. No ultimatums, just invasion. Also, the French Army would have required a change of philosophy, since IIRC they were more concentrated on defence than on offensive actions.
Nevertheless, IMHO a quick, decisive and earlier prepared offensive (i.e. what the Allies had promised the Poles) might change a lot.
A psychological factor would be enormous - Hitler was shocked when the Britain and France declared war on Germany IOTL, only after he realized there would be no serious action in the west he regained his confidence. However, with Franco-British armies pushing from west the German military commanders might decide to act.
German forces in the west were weak, and Siegfired Line was never really tested - I think the French, with their heavy artillery, might have been able to break it. After that they might easily march until the Rhine and had they manage to cross it, well, the Ruhr region would be in trouble.
The USSR might dedice to sit it out, as IOTL Stalin waited with his invasion of Poland until he knew the Allies would not attack. When Ribbentropp starts screaming about their pact the Soviets would say: we signed only a non-agression pact; there was no secret protocol at all, no way, comrades.
Invasion of Poland would not come to a halt, but the Germans would need to transfer at least some of their units to the west, which might give the Poles some time to catch their breath. A lot depends of the speed and degree of success of allied attack.
Of course if France and Britain mobilize before the invasion of Poland it might even force Hitler to call his attack off. But it would require a significant change in alied foreign policy in 1939. IOTL they tried to avoid the war until the last minute, even forcing Poles to call off their mobilization in late August 1939, since it might "provoke" teh Germans (the fact that German Army was already mobilized and on Polish border somehow eluded them).
 
Which whole Army?

The peacetime one? Or the fully mobilised one?

OTL, neither was available, as the peacetime army was providing the cadre for the wartime one and so was being disbanded.

SO either an earlier mobilisation is needed, as said above, or the entente must attack with it's peacetime army. Which is a huge gamble, as if this attack is slaughtered, as WWI experience would attack, they don't have any experienced personnel left to build another army around. I don't see the later happening, as this is too risky, unless you change the whole French general officiers corp and all the leading politicians.
 
If France managed to gather courage for this in 1939, then they would also most likely have been more decisive in 1938 and Munich never happens, Hitler is deposed by the Heer and WW2 is averted. Germany goes on to default, inflation, civil unrest, civil war, authoritarian military regime rules to 1960's, free elections, convergence to OTL.

The point is that you can't just suddenly have the French do the thing they allowed Munich to happen. And still have Munich happen.
 
The point is that you can't just suddenly have the French do the thing they allowed Munich to happen. And still have Munich happen.

Could you get enough dissent in France that while Munich does happen, the failure of it is seized on as a reason for harsher action next time?
 
If France managed to gather courage for this in 1939, then they would also most likely have been more decisive in 1938 and Munich never happens, Hitler is deposed by the Heer and WW2 is averted. Germany goes on to default, inflation, civil unrest, civil war, authoritarian military regime rules to 1960's, free elections, convergence to OTL.

The point is that you can't just suddenly have the French do the thing they allowed Munich to happen. And still have Munich happen.

It's a bit disingenious to blame Munich on the French as they, as always in the 30s, followed the british diplomatic lead. Averting Munich is not a matter of French 'gathering courage'; either the british do so or the french have to break from the british diplomatically. The only way for either to occur is for the political and military leadership to believe they can stand up to Germany in 38 (they could, but due to German propaganda, they didn't think so). So you have to have either franco/british rearmament starting earlier or their intelligence and military leadership apparatus not taken in by German propaganda.
 
It's a bit disingenious to blame Munich on the French as they, as always in the 30s, followed the british diplomatic lead. Averting Munich is not a matter of French 'gathering courage'; either the british do so or the french have to break from the british diplomatically. The only way for either to occur is for the political and military leadership to believe they can stand up to Germany in 38 (they could, but due to German propaganda, they didn't think so). So you have to have either franco/british rearmament starting earlier or their intelligence and military leadership apparatus not taken in by German propaganda.

But Czechoslovakia was a French ally, not the British. Why did the French allow themselves to get in a situation were the future of their ally is decided without the consent of said ally? For that matter, France started on a slippery slope once they consented to the German unilateral occupation of Rheinland. Each step afterwards was just the matter of well, if you were afraid of Germans when they had nothing, how are we going to face them now, that they have the fortifications?
 
I wrote an (incomplete) scenario on this in my signature, along with a novel based on the scenario. The novel is presently being re-edited for a second edition (no major plot changes, but the writing style needs improvement). The POD is that Daladier is removed as Prime Minister after Hitler reneges on the Munich Agreement and annexes Czech. Daladier is replaced by Paul Reynaud, a much more decisive leader who was awake to the true threat of Germany very quickly, within a few months he replaces the hapless Gamelin as Army chief, and France is prepared to invade Germany in the first few days (Separately Poland mobilises earlier as well, slowing the German advance slightly compared to OTL). In OTL he became PM a month before the Fall of France, in my scenario he becomes PM a year earlier.

Ultimately the scenario leads to the early defeat of Germany, with the Wehrmacht stepping in and restoring the constitutional monarchy.
 
The POD is that Daladier is removed as Prime Minister after Hitler reneges on the Munich Agreement and annexes Czech. Daladier is replaced by Paul Reynaud, a much more decisive leader who was awake to the true threat of Germany very quickly, within a few months he replaces the hapless Gamelin as Army chief, and France is prepared to invade Germany in the first few days (Separately Poland mobilises earlier as well, slowing the German advance slightly compared to OTL). In OTL he became PM a month before the Fall of France, in my scenario he becomes PM a year earlier.

But, even after he became Prime minister, Reynaud had to deal with Daladier, who remained the Minister of defence and war. As such, it would be in Daladier's purview to change the Supreme commander. And he and Gamelin were budies. IIRC. Besides, the French army higher officers uniformly shared the belief that defense was superior. Their doctrine was not well suited for offensive. They would take weeks if not a month or two to prepare the attack on the Sigfried line. By that time it would be over for Poland.

I am not saying it is impossible, but it would take a staggering amount of luck and prescience for the French for something like this to happen.
 
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It's a bit disingenious to blame Munich on the French as they, as always in the 30s, followed the british diplomatic lead. Averting Munich is not a matter of French 'gathering courage'; either the british do so or the french have to break from the british diplomatically.
Check books on the topic. Now we even have the official letters. Basically French said "we go if you go". Brits said "ok, let's check with the military". Theu told them "ok, 250 planes no more, two divisions, no more". At the same time French would have had to deploy at least 1000 planes, mobilize and deploy no less than 60-80 divisions. The French answer was "you're kidding me, we're allies but who's going to pay, to get the bombing and the dead soldiers?". Neither went...

At the same time you will notice that the best German ally was... Poland (!!!).

They would take weeks if not a month or two to prepare the attack on the Sigfried line. By that time it would be over for Poland.

Not exactly: they were expecting Poland to last much longuer, giving them time to act. The limited offensive in 39 was effective: the idea was to reach the Siegfried line to deploy artillery.
 
I wrote an (incomplete) scenario on this in my signature, along with a novel based on the scenario. The novel is presently being re-edited for a second edition (no major plot changes, but the writing style needs improvement). The POD is that Daladier is removed as Prime Minister after Hitler reneges on the Munich Agreement and annexes Czech. Daladier is replaced by Paul Reynaud, a much more decisive leader who was awake to the true threat of Germany very quickly, within a few months he replaces the hapless Gamelin as Army chief, and France is prepared to invade Germany in the first few days (Separately Poland mobilises earlier as well, slowing the German advance slightly compared to OTL). In OTL he became PM a month before the Fall of France, in my scenario he becomes PM a year earlier.

Ultimately the scenario leads to the early defeat of Germany, with the Wehrmacht stepping in and restoring the constitutional monarchy.
Germany didn't technically annex Czech. It created the Protectorate of Bohemia and Moravia.
 
I wrote an (incomplete) scenario on this in my signature, along with a novel based on the scenario. The novel is presently being re-edited for a second edition (no major plot changes, but the writing style needs improvement). The POD is that Daladier is removed as Prime Minister after Hitler reneges on the Munich Agreement and annexes Czech. Daladier is replaced by Paul Reynaud, a much more decisive leader who was awake to the true threat of Germany very quickly, within a few months he replaces the hapless Gamelin as Army chief, and France is prepared to invade Germany in the first few days (Separately Poland mobilises earlier as well, slowing the German advance slightly compared to OTL). In OTL he became PM a month before the Fall of France, in my scenario he becomes PM a year earlier.

Ultimately the scenario leads to the early defeat of Germany, with the Wehrmacht stepping in and restoring the constitutional monarchy.

Where can I get that book?
 
Didn't France do a temporary and utterly ineffective incursion IOTL? I seem to remember something about a village or two either briefly occupied or scouted...
 
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