Britain and France invade Germany after Germany invades Poland

[Julian]

The Saar was something like 1/3 of iron production and 1/4 of steel, so even a modest French penetration into the Saarland would have serious consequences for Germany's war economy. A German counteroffensive is almost certainly guaranteed if the French achieve any sort of success.

IOTL September 1939, France was unprepared to go on the offensive and had little interest in preparing to do so. I could see interwar French doctrine leaning towards a "bite and hold" early M+15 offensive in the Saar given their sensitivity towards border resources - if it hurt so badly when the Germans seized France's frontier resources, why not do the same to them? There were also plenty of fears about a shallow German penetration towards Metz and Alsace to seize French resources. Seizing a buffer was seen as a sensible solution to these worries. This requires doctrinal PODs in the 1920s or 1930s but I think it's feasible and has a high chance of being rewarding. Even in 1936, when the chance for an initial strong blow may have already been rendered structurally infeasible, Gamelin offered occupying Luxembourg and parts of the Saar as a potential preliminary option to a fully mobilized offensive to drive Germany from the Rhineland.

 

[DracoLazarus]

The Saar was something like 1/3 of iron production and 1/4 of steel, so even a modest French penetration into the Saarland would have serious consequences for Germany's war economy. A German counteroffensive is almost certainly guaranteed if the French achieve any sort of success.

IOTL September 1939, France was unprepared to go on the offensive and had little interest in preparing to do so. I could see interwar French doctrine leaning towards a "bite and hold" early M+15 offensive in the Saar given their sensitivity towards border resources - if it hurt so badly when the Germans seized France's frontier resources, why not do the same to them? There were also plenty of fears about a shallow German penetration towards Metz and Alsace to seize French resources. Seizing a buffer was seen as a sensible solution to these worries. This requires doctrinal PODs in the 1920s or 1930s but I think it's feasible and has a high chance of being rewarding. Even in 1936, when the chance for an initial strong blow may have already been rendered structurally infeasible, Gamelin offered occupying Luxembourg and parts of the Saar as a potential preliminary option to a fully mobilized offensive to drive Germany from the Rhineland.

Wouldn't the Saargebiet's siderurgic industry already be badly hit by the lack of access to Lorrain iron ores ?
From what I understand, when it came to industrializing the greater Rhine-Moselle region, the limiting factor generally seemed to be access to coal, not iron ore. However, that was because Lorrain iron ore deposits (minette) were stupidly abundant (I think it was estimated that during WWII France sat on one third of the European iron ore supply), making for cheap, albeit poor ores.
However, this means that it was simpler to just import ores. And in 1939, unlike 1914-1918, Germany does not have any of said ores under its control - Briey-Longwy stayed in French hands, and Thionville was reconquered at the 1918 armistice. I suppose therefore that the Sarrois industry may have kept on relying on French ores, unlike industry further North which shifted to higher-quality Swedish ores.
This is important because changing the ore's origin means changing the ore's composition, which means the process to remove impurities is different; there would need to be a production gap several months long when French ores ceased being available in order to retool for Swedish ores. Such a production gap would greatly decrease the strategic importance of the Saargebiet on the short-term.

 

[Julian]

Wouldn't the Saargebiet's siderurgic industry already be badly hit by the lack of access to Lorrain iron ores ?
From what I understand, when it came to industrializing the greater Rhine-Moselle region, the limiting factor generally seemed to be access to coal, not iron ore. However, that was because Lorrain iron ore deposits (minette) were stupidly abundant (I think it was estimated that during WWII France sat on one third of the European iron ore supply), making for cheap, albeit poor ores.
However, this means that it was simpler to just import ores. And in 1939, unlike 1914-1918, Germany does not have any of said ores under its control - Briey-Longwy stayed in French hands, and Thionville was reconquered at the 1918 armistice. I suppose therefore that the Sarrois industry may have kept on relying on French ores, unlike industry further North which shifted to higher-quality Swedish ores.
This is important because changing the ore's origin means changing the ore's composition, which means the process to remove impurities is different; there would need to be a production gap several months long when French ores ceased being available in order to retool for Swedish ores. Such a production gap would greatly decrease the strategic importance of the Saargebiet on the short-term.

Great point! Doing more reading it looks like the region's furnaces were damped for several months in Fall 1939 due to just the reasons you suggest, along with worries about vulnerability to invasion. The region's production in the Fall dropped 85% as a result. German monthly ingot steel production dropped from 2 million tons in August to 1.67 million in September before recovering to about 1.73 million for the rest of the Fall. That would mean I was incorrect on numbers, Saar production in 1939 would be closer to 12% of iron, 11% of steel and 8% of coal. I'd stand by the overall point that despite temporary difficulties in the region, it was of significance to Germany and allowing it to be occupied long term would be unacceptable. Given how serious coal bottlenecks alone were in Winter 1939-40, because of how severe that winter was, losing production would be worrying. Germany's economy in 39-40 was really working on a shoestring resources budget.

On an economic note alone, allowing France to continue occupying the Saar partially or completely would be unacceptable. Because of how it increased vulnerabilities in the rest of the Rhineland, this doubles the potential threat of a penetration in the Siegfried Line. Given that Germany was unaware of how France qualitatively compared to their own armed forces, it couldn't assume that a penetration in the Saar couldn't be capitalized on.

I don't think the French Army could hold the region (Probably), but fighting a large-scale engagement with the Germans would have a stimulating effect on combing out poor leaders, adopting better tactics, and generally giving the French military its acid test. I also think that it may have calcified in Hitler's mind the need to launch a swift offensive, by January at the latest, in order to better secure buffer space against further attacks and divert the French military away from the border.

 

[Cryhavoc101]

France told Poland that in the event of a German Attack on them they would attack Germany 14 days after they declared war (3rd Sept) as it took that long to mobilise the French Army etc

That would be on or about the 17th Sept

Can anyone tell me what else happened that day that might have given the French reason to change their minds?

So only if the French were ready earlier i.e. had begun to mobilise earlier than 3rd Sept could they have begun a serious attack into the Ruhr before the 17th ideally in the first week of Sept might some thing have been achieved.

 

[AMBOMB]

But suppose the British and French had had their forces in an offensive position along the French German border ready to invade Germany as soon as the Germans invaded Poland.

 

[Barry Bull]

Well as the French troops demonstrated during and after the Dunkirk evacuation they weren't lacking in fighting spirit or ability. In 1939 with better leadership and maybe if the Germans did something stupid in the west that fired them up they could do some serious damage. Of course the question is how far would they have to get before panic breaks out in Berlin?

Have you read the posts linked by @David T ?

Have you considered that the French Army was simply not ready in 1939, just like the Red Army in 1941?

There was a limited French offensive. That much more was possible before the collapse of Poland is doubtful, as Michele has endlessly pointed out both in soc.history.what-if and here. https://www.alternatehistory.com/forum/threads/france-and-britain-really-invade-germany-in-1939.254232/#post-6655192
https://www.alternatehistory.com/forum/threads/france-and-britain-really-invade-germany-in-1939.254232/#post-6655269
https://www.alternatehistory.com/fo...y-invade-germany-in-1939.254232/#post-6655499

WI: France invades Germany in 1939

soc.history.what-if.narkive.com

 

[Garrison]

Have you read the posts linked by @David T ?

Have you considered that the French Army was simply not ready in 1939, just like the Red Army in 1941?

Yes I have considered it, which is why we've been discussing ways in which it might be able to do better. The question should be is it an actual lack of capability on the part of the French that prevents a more aggressive strategy or is the blame primarily on poor leadership. The strategic surprise achieved by the Wehrmacht in 1940 makes it hard to be fully objective about the French in 1939.

 

[Julian]

I think the big limitation on French capabilities was the lack of large engagements before May 1940 from which they could sort out the kinks in their military. Because most of their armed forces were decisively defeated so quickly in May-June, the actual invasion gave them no time to learn "on the job" as they very successfully did in August-September 1914. Even an ultimately unsuccessful large Saar engagement would provide significant knowledge. Beyond that, as I mentioned above, it's hard to imagine Hitler countenancing a delay until May if the French have demonstrated the willingness and ability to cross the border into the Rhineland. Therefore you're likely to see the original Fall Gelb implemented in December once the French have been expelled from the Saar, with the main blow along the Maas and meeting engagements in Central Belgium.

 

[Deleted member 1487]

I think the big limitation on French capabilities was the lack of large engagements before May 1940 from which they could sort out the kinks in their military. Because most of their armed forces were decisively defeated so quickly in May-June, the actual invasion gave them no time to learn "on the job" as they very successfully did in August-September 1914. Even an ultimately unsuccessful large Saar engagement would provide significant knowledge. Beyond that, as I mentioned above, it's hard to imagine Hitler countenancing a delay until May if the French have demonstrated the willingness and ability to cross the border into the Rhineland. Therefore you're likely to see the original Fall Gelb implemented in December once the French have been expelled from the Saar, with the main blow along the Maas and meeting engagements in Central Belgium.

Yes and no. You're basic premise is right, but the problem is France was at peak manpower in 1940, so substantial losses in 1939 would cripple them, as they could not afford even a 1:1 casualty ratio with Germany and they certainly weren't even close to that IOTL 1939. They suffered a 3:1 loss ratio during their 1939 offensive IOTL, which is completely unsustainable for them and attacking into the West Wall, even if not complete or nearly as tough as the Maginot Line, is only going to result in unaffordable loss ratios especially when reinforcements from Poland show up, especially in the air. Plus the terrain is really not in the attacker's favor especially given mines and mortars/artillery and air attack. Even assuming they improve their OTL casualty ratio down to 2:1 casualties if they suffer 20k or more losses they're getting much more relatively weak compared to the Germans and the losses are going to be among their best troops, as only the most prepared to go are available in 1939, i.e. the young men in the standing, professional army, while IOTL the Saar offensive was really only opposed by 3rd line German troops that were poorly equipped and older WW1 vets.

If German forces have to expend munitions and men defending the Saar there is no way they can invade France in December 1939 or any time that winter, because they would be WAY too low on ammo after the Polish campaign and defeating the French invasion. If anything it delays the 1940 offensive into Summer...which might provide the Allies enough time to launch Operation Pike, which would utterly screw them.

 

[Julian]

Yes and no. You're basic premise is right, but the problem is France was at peak manpower in 1940, so substantial losses in 1939 would cripple them, as they could not afford even a 1:1 casualty ratio with Germany and they certainly weren't even close to that IOTL 1939. They suffered a 3:1 loss ratio during their 1939 offensive IOTL, which is completely unsustainable for them and attacking into the West Wall, even if not complete or nearly as tough as the Maginot Line, is only going to result in unaffordable loss ratios especially when reinforcements from Poland show up, especially in the air. Plus the terrain is really not in the attacker's favor especially given mines and mortars/artillery and air attack. Even assuming they improve their OTL casualty ratio down to 2:1 casualties if they suffer 20k or more losses they're getting much more relatively weak compared to the Germans and the losses are going to be among their best troops, as only the most prepared to go are available in 1939, i.e. the young men in the standing, professional army, while IOTL the Saar offensive was really only opposed by 3rd line German troops that were poorly equipped and older WW1 vets.

If German forces have to expend munitions and men defending the Saar there is no way they can invade France in December 1939 or any time that winter, because they would be WAY too low on ammo after the Polish campaign and defeating the French invasion. If anything it delays the 1940 offensive into Summer...which might provide the Allies enough time to launch Operation Pike, which would utterly screw them.

Well let's be clear, the French suffered greater losses in what were a series of uncoordinated, half-assed skirmishes intended to score some propaganda wins. Artillery and armor was never seriously brought forward, which is why for practical purposes the offensive halted in front of the West Wall and never tried to penetrate it. I think it's apples to oranges to compare a fighting retreat over prepared ground against an un-enthusiastic demonstration to a hypothetical prepared attack to penetrate the West Wall. Fire superiority-breakthrough-dominate/maneuver-repeat were exactly what the French army had been built around since the 1920s, and given that it did perform well on plenty of occasions in 1940 against quality German divisions there's no reason to think it couldn't crack the West Wall, overrun the defending Germans, and inflict heavy losses in the initial phase of fighting.

In regards to manpower, I think you overstate France's disadvantage. While it's indisputable that Germany had a 2:1 advantage in military-aged manpower in 1939, let's not forget that it also had a 1.7:1 advantage in 1910! While in the long-term this would indeed ensure France's defeat in isolation (As it would've in 1914), France would be supplemented by a 1 million man British army by the end of 1940 and 2 million by 1941. While we can wonder about whether the Franco-British alliance in isolation could have sustained war against Germany alone for many years, certainly in the timeframe of 1939-41 they could field forces to adsorb losses and maintain sizable armies, especially with improved performance over time.

German capabilities were of course low even IOTL Winter 1939-1940, which didn't really stop Hitler from wanting to go ahead with risky offensives. Beating back a major French offensive in the Saar certainly harms those capabilities - how much in the long run depends on the specifics - but it also creates an urgent need for Germany to assume the strategic initiative. Its armaments programs weren't expected (Correctly) to hit full stride until summer-fall 1940. Sitting on the defensive when the French are showing no sign of going on the attack is one thing, sitting and waiting when France has already shown the willpower and capability to threaten Germany's industrial heartland is another. Even if a major offensive isn't attempted, an attack around Luxembourg to threaten the Briey-Longwy iron mines and seize Maas bridgeheads/divert French reserves would be a potential alternative.

Anyway, if it seems likely for Germany to wait until Summer 1940 I don't see Pike happening. Even IOTL it wasn't likely the War Cabinet would ever approve it, they were quite cautious about avoiding provoking a German-Soviet alliance unless it appeared to be certain anyways. ITTL its creation at all seems uncertain. It was a product of the Sitzkrieg, stemming from an urgent desire by the French (Who were the most pushy about the plan) and the UK to do something somewhere which would hurt Germany. Norway alone was enough to put the plan on the backburner altogether. If the Allies are already taking the fight to Germany on its home turf, that anxiety no longer exist.

 

[Deleted member 1487]

Well let's be clear, the French suffered greater losses in what were a series of uncoordinated, half-assed skirmishes intended to score some propaganda wins. Artillery and armor was never seriously brought forward, which is why for practical purposes the offensive halted in front of the West Wall and never tried to penetrate it. I think it's apples to oranges to compare a fighting retreat over prepared ground against an un-enthusiastic demonstration to a hypothetical prepared attack to penetrate the West Wall. Fire superiority-breakthrough-dominate/maneuver-repeat were exactly what the French army had been built around since the 1920s, and given that it did perform well on plenty of occasions in 1940 against quality German divisions there's no reason to think it couldn't crack the West Wall, overrun the defending Germans, and inflict heavy losses in the initial phase of fighting.

Care to cite any examples of when the French attacked with success in terrain like that of the Saar region? Lots of forests, hills, and mines. The only time they did fight effectively was on the defensive in relatively flat terrain in Belgium.

Were it so easy for the French to do so...why did they do it IOTL in 1939?

In regards to manpower, I think you overstate France's disadvantage. While it's indisputable that Germany had a 2:1 advantage in military-aged manpower in 1939, let's not forget that it also had a 1.7:1 advantage in 1910! While in the long-term this would indeed ensure France's defeat in isolation (As it would've in 1914), France would be supplemented by a 1 million man British army by the end of 1940 and 2 million by 1941. While we can wonder about whether the Franco-British alliance in isolation could have sustained war against Germany alone for many years, certainly in the timeframe of 1939-41 they could field forces to adsorb losses and maintain sizable armies, especially with improved performance over time.

End of 1940 the British weren't on the continent anymore. The French had to think of preserving manpower until their industry and US purchases could get in gear and survive 1940 so they could launch strategic offensives in 1941. The British in May 1940 weren't a particularly decisive force on the continent and the Belgians weren't working with the French or British.

So you're not really getting at the core issues the French were preoccupied with IOTL. Later I can post a link to an article that detail the extreme pessimism the French government had for fighting offensively in Europe against the Germans (and have posted several times here before in regards to why they were enthusiastic about Operation Pike) as well as having been duped by German propaganda about the size of the Luftwaffe and strength of the Siegfried Line.

Also you're forgetting the French did not want to repeat the losses of WW1, because they saw what happened to their population/birthrates and economy; they needed to preserve men to actually run the country after the war and didn't want to have to keep importing foreign men to sustain the economy and make up for the horrible female:male population ratios among child-having age cohorts.

German capabilities were of course low even IOTL Winter 1939-1940, which didn't really stop Hitler from wanting to go ahead with risky offensives. Beating back a major French offensive in the Saar certainly harms those capabilities - how much in the long run depends on the specifics - but it also creates an urgent need for Germany to assume the strategic initiative. Its armaments programs weren't expected (Correctly) to hit full stride until summer-fall 1940. Sitting on the defensive when the French are showing no sign of going on the attack is one thing, sitting and waiting when France has already shown the willpower and capability to threaten Germany's industrial heartland is another. Even if a major offensive isn't attempted, an attack around Luxembourg to threaten the Briey-Longwy iron mines and seize Maas bridgeheads/divert French reserves would be a potential alternative.

Hitler wanted to and his generals convinced him not to. Not only that, but they were going to coup him if he ordered an offensive that winter. If he tries, he dies. Having fought off a French offensive will mean an offensive against the French outside the Saar region is simply impossible. Defeating the French actually reduces the need for a German offensive immediately, because the French have been beaten and the Allies aren't going to violate the neutrality of Belgium or the Netherlands. Plans to invade Norway were already underway by early 1940 IIRC and the January 1940 incident that revealed the German invasion plan to the Belgians meant the entire invasion had to be called off until a different one could be drafted.

The Saar isn't the German industrial heartland and a defeated French offensive only shows that the French are incapable of being a threat, so again the pressure is actually not on to attack immediately; in fact if anything it secures the Rheinland because the best French effort possible for at least the next 6 months has been dealt with. The French weren't going to violate a neutral country so visibly to attack Germany, the optics were too bad at that point, plus Luxembourg is not good attack country, especially given that the French themselves largely considered that region terrible offensive terrain. I'm sure the 1914 defeat there reinforced their view.

Anyway, if it seems likely for Germany to wait until Summer 1940 I don't see Pike happening. Even IOTL it wasn't likely the War Cabinet would ever approve it, they were quite cautious about avoiding provoking a German-Soviet alliance unless it appeared to be certain anyways. ITTL its creation at all seems uncertain. It was a product of the Sitzkrieg, stemming from an urgent desire by the French (Who were the most pushy about the plan) and the UK to do something somewhere which would hurt Germany. Norway alone was enough to put the plan on the backburner altogether. If the Allies are already taking the fight to Germany on its home turf, that anxiety no longer exist.

It was already underway and only delayed due to the invasion of France in May:

Operation Pike - Wikipedia

en.wikipedia.org

As of 1 April, four squadrons comprising 48 Bristol Blenheim Mk IV bombers were transferred to the Middle East Command, supplemented with a number of single-engined Wellesley bombers for night missions. A French force of 65 Martin Maryland bombers and a supplementary force of 24 Farman F.222 heavy bombers were allocated for night operations during the campaign. The French were preparing new air fields in Syria which were expected to be ready by 15 May. The campaign was expected to last three months and over 1,000 short tons (910 t) of bombs were allocated to the operation: 404 × 500 lb (230 kg) semi-armour-piercing bombs, 554 × 500 lb (230 kg) and 5,188 × 250 lb (110 kg) general-purpose bombs and 69,192 × 4 lb (1.8 kg) incendiary bombs.[12]

The German Blitzkrieg and the swift fall of France on 10 May 1940 derailed the plans, when the French military failed to hold back the Wehrmacht advance. The Germans captured a train stalled at the village of La Charité-sur-Loire that contained boxes of secret documents evacuated from Paris. Amongst these were documents dealing with Operation Pike. On 4 July, in a propaganda campaign to justify the invasion of France, the Deutsches Nachrichtenbüro (DNB, German News Bureau) released excerpts of the captured documents relating to Operation Pike, asserting that

Germany must be credited with saving these other states [including the Soviet Union] from being drawn into this chaos by Allied schemings .... because she took timely counter-measures and also crushed France quickly.
— DNB[13]

The strategic Anglo-French bombing campaign against Soviet targets was postponed and eventually abandoned.[14]

The reason it was abandoned was the Germans captured the plans and publicized them, which meant it couldn't be launched since the Soviets were alerted.