Could a German invasion of Turkey succeed?

[Avalancheon]

Thus, a force of 10 infantry and 10 panzer divisions would need 5600 tons of supplys a day.

There's a range of variance about what would be needed but I'm fine with that figure as well for ATL purposes. The very concept of "needed" has some ambiguity - it could range from "average ideal" through "minimum for success" to "minimum for survival." German mechanized units at the bleeding edge of deep operations in Barbarossa seem to have operated on far less against strong Soviet reserves; probably a German unit facing a quantum of poorly-equipped Turks needs less supply than one facing an equal quantum of Soviets.

No arguments there. In terms of equipment, the Turks were much worse off than the Soviets. They had hardly any tanks or anti-tank guns, which would put them at a huge disadvantage against the Germans. The shortages of artillery, motor vehicles, and radios are additional factors that will handicap the Turks. The Heer will have a much easier time against them than the Red Army. The initial German attack into Thrace would be a clean sweep. Constantinople would probably be in their hands within about a week or so.

Peter89s estimate on the capacity of a single track railway are unrealistically low. He says 10 train (pairs) per day, but in fact it was 12. More importantly, it was possible to greatly improve the capacity of a single track line, to the point where they could handle 72 train (pairs) per day. (Thats an increase of 6 times) This is explained in the article, The Influence of Railways on Military Operations in the Russo-German War 1941–1945, by H.G.W. Davie.

Don't you know the Germans are not allowed to act rationally in any respect whatsoever?

Seriously it's a point I made upthread (loooong thread though) and whose logic is just unavoidable. As Davie's article discusses, Germany carried off probably the largest pre-operation rail program in history ahead of Barbarossa (Operation Otto), laying 300,000 tons of steel. That's probably on the order of total track weight in the Balkans at that time. To pretend they can't upgrade Turkey-bound railways is pure fantasy. Germany upgraded rail connections to the French frontier ahead of Fall Gelb as well. Nonetheless there's a fad about Germans and logistics; it's impervious to evidence.

It is a weird argument to make, no question. Peter89 seems to think that there is some iron law of nature preventing the Bulgarian railway from operating more than 10 trains per day. The volume of trains it historically supplied is the maxiumum volume it could ever supply, regardless of any improvements. He doesn't give any reasons why this is so, he just waves his hands and expects us to take it at face value.

The problemis that the Western Allies had a pretty good railroad network towards Turkey by late 1942, with multiple ports, airfields and whatnot.

The problem for the Allies is shipping more than rails and ports (which were worse than in Turkey anyway, btw - one decent line from Basra that needed upgrading and one incomplete line in Palestine/Levant). Peter89 upthread admits to being unable to quantify the shipping factor (hope I don't have to find that post but will do so if challenged); his faith that the W.Allies could fight extensively in the ME lacks analytical grounding.

Yes, the Middle Eastern railroads were very deficient. This doesn't directly relate to the subject at hand, BUT... It is interesting to speculate what consequences this could have had in another timeline, if the battle of El Alamein had gone differently.

If the Germans had succeeded in pushing the British out of Egypt, then they would have had a very difficult time supplying their forces in Palestine and TransJordan. The British would have needed to ship supplys in to the port of Basra in Iraq. Then transport them on the Taurus railway from Basra to Aleppo in Syria. And then transport them again over a different railway from Aleppo to Haifa in Palestine. Thats an enormous distance to cover, and supply volumes cannot have been very great.

Meanwhile, the Germans would have a much easier time suppling their forces in Egypt. They would have control of the huge port of Alexandria, not to mention the smaller ports of Said and Suez. The railway lines were short and direct, enabling them to quickly move large supply volumes to the front. The Middle East would be indefensible against them. So you see, a British defeat at El Alamein would have really screwed them over in the long run, because their logistical situation would be untenable.

if instead of Blue or Citadel, the Germans had invaded Turkey without one word of discussion with Stalin

German invasion of Turkey doesn't make sense unless SU is defeated.

...Or unless they invade in conjunction with the Soviet Union.

[Peter89]

Peter89s claims about the supply requirements of a German division seem to check out. According to this site: http://www.mnstarfire.com/ww2/history/l ... ision.html

''A typical full strength infantry division would consist of roughly 17,000 men. Prior to 1944 a German infantry division would include over 5,000 horses and almost 950 motor vehicles. A division of this size would need 53 tons of hay and oats, 54 tons of food, 20 tons of petrol, one ton of lubricants, ten tons of ordinance and another 12 tons of miscellaneous supplies plus ammunition and baggage (approx 150 tons total per day).''

''A Panzer or Armored Division would be roughly 14,000 men. Usually there would be over 3,000 vehicles... The supply requirement for an average of motorized, mechanized and panzer divisions has been stated as approximately 300 tons per day.''

IIIRC my numbers came from here: https://www.ibiblio.org/hyperwar/Germany/HB/HB-6.html

Okay, no problems here.

However, this figure does not include ammunition consumption. For some idea of what their ammo needs are, we can look to the Eastern front. In August of 1941, Franz Halder noted that the Ostheer had expended 340 trainloads of ammunition during a 15 day period. This means they were consuming an average of 8220 tons ammunition per day on the Eastern front. Spread out across 150 divisions, that works out to about 55 tons per division, per day.

So when adding in ammunition requirements on top of their regular needs, the infantry divisions would each need 205 tons of supplys a day, and the panzer divisions would need 355 tons a day.

Thus, a force of 10 infantry and 10 panzer divisions would need 5600 tons of supplys a day.

Please check again on the ammunition consumption.

(3) Ammunition supply trains (Munitionszüge), with an average of 30 cars per train, are of three types:
(a) Unit-loaded trains, loaded according to the proportion of different types of ammunition needed by a particular division.
(b) Caliber unit trains, in which each car is loaded with approximately 15 metric tons (161/2 short tons) of ammunition of a specific caliber.
(c) Single caliber unit trains, in which all cars are loaded with ammunition of the same caliber.

Alright, so an ammunition train of 30 cars, at 15 tons each, can carry 450 tons of ammunition.

340 trainloads of ammunition over a 15 day period comes out to about 10,200 tons per day. Not 8220 tons per day. Ammunition consumption is 24% greater than what I stated [].


[] FYI, I got these figures from the CIA document, The Eastern Front at the Turning Point. https://www.cia.gov/library/center-for- ... i4a07p.pdf

Also, the Bulgarian railway, the only way where you could transport stuff was good for 2/3 cargo only.

And why is that? Explain, please.

Peter89s estimate on the capacity of a single track railway are unrealistically low. He says 10 train (pairs) per day, but in fact it was 12. More importantly, it was possible to greatly improve the capacity of a single track line, to the point where they could handle 72 train (pairs) per day. (Thats an increase of 6 times) This is explained in the article, The Influence of Railways on Military Operations in the Russo-German War 1941–1945, by H.G.W. Davie.

36 trains per day in this direction is an illusion. The Germans might rebuild the whole railway on the Balkans, making it double track and everything, but it's not gonna happen soon, and by this standard, they could have built a railway anywhere, anytime.

No, it is not an illusion. Again, as the article in question points out, a single track railway can theoretically get up to a maximum of 72 train pairs per day. To get 36 train pairs per day should be feasible. Is there anything you can explicitly point to that would make this impractical?

You see, "one train" can be translated into many, very different types of supply and troops, my numbers are representing a theoretical maximum, without the "Balkan load" limit.

Whats that supposed to mean?

Obviously, the economic exploitation of the Balkans cannot stop forever, and the Bulgarian domestic economy can't be stopped forever.

If you plan a short-term offensive, then you might build up and load forward supply depots, but to operate 5+5 divisions fighting heavily on the offense using this railway line is a daydreaming.

You claim, but you do not so demonstrate.

I quoted exactly S.H. Beaver that he estimated 12-20 trains per day for a single standard gauge track railway; I used 10 trains per day as a very optimistic number, because in order to achieve that, a lot of things must happen right, which they usually didn't.

Is that so? I didn't see you quoting him anywhere. Give me that citation from Beaver, and we'll see whether it has any merit.

10 trains per day is far below the theoretical maximum capacity of a single track line. 12 trains per day is usually the lower limit, and 72 trains per day is the upper limit.

I don't really understand you; you say that my numbers are "unrealistically low", because I used 10 trains per day and you used 12.
Did you check the numbers of the Bulgarian domestic economy? Their typical cargo and train types? Did you substracted it from the 12?

Again, I have no idea what you are referring to. You didn't mention any of this in the quote I was responding to here viewtopic.php?p=2292406#p2292406

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

[glenn239]

German invasion of Turkey doesn't make sense unless SU is defeated.

A German invasion of Turkey made perfect sense for the reasons already described; those that have already lost their do-or-die gambles cannot then get picky about the desperation plays to pick up the pieces.

Germany could not win the war militarily once it decided to invade the Soviet Union, because the Soviet Union could not be defeated by Germany and the SU possessed the resources to overwhelm Germany's armies and occupy its homeland. Therefore, the only feasible strategy for Germany after Barbarossa failed was the political strategy of dividing east from west. Operations such as Blue and Typhoon were Hitler simply repeating his original fatal error in a weaker and weaker fashion, with no prospect of anything approaching a strategic success to alter the trajectory of the war. To cause Stalin not to take Berlin, the Germans had to give him an alternative while they withdrew out of his country.

[TheMarcksPlan]

Germany could not win the war militarily once it decided to invade the Soviet Union

I'm aware we disagree on that issue...

If you're right about SU then there's sense in your argument. If I'm right there's there's not. Not really the thread to hash that out; I welcome your participation in any of my numerous threads on the topic.

[Avalancheon]

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

You made the claims, its on you to back that up.

[Peter89]

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

You made the claims, its on you to back that up.

Which I did, so please do read the references.

I am no assistant of anyone.

[Avalancheon]

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

You made the claims, its on you to back that up.

Which I did, so please do read the references.

I am no assistant of anyone.

In the comment of yours that I replied to? No, you did not.

Whatever explanations you gave are scattered across 12 pages. I'm not going to wade through all of that.

[Peter89]

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

You made the claims, its on you to back that up.

Which I did, so please do read the references.

I am no assistant of anyone.

In the comment of yours that I replied to? No, you did not.

Whatever explanations you gave are scattered across 12 pages. I'm not going to wade through all of that.

Then I care not to answer your already answered questions.

[Terry Duncan]

All the answers you are looking for are decently cited in the previous comments, so why don't you make an effort and actually read them?

You made the claims, its on you to back that up.

Which I did, so please do read the references.

I am no assistant of anyone.

In the comment of yours that I replied to? No, you did not.

Whatever explanations you gave are scattered across 12 pages. I'm not going to wade through all of that.

Then perhaps it would have been better for you to have adopted a more polite tone in the first place? Civility is a prerequisite for being a member on this site not an optional feature you can opt out of at will, so, having had two posts deleted in as many days by senior moderation staff it is only fair to warn you that any further breaches of the rules will likely lead to a suspension.

Terry Duncan

[glenn239]

If you're right about SU then there's sense in your argument. If I'm right there's there's not. Not really the thread to hash that out; I welcome your participation in any of my numerous threads on the topic.

In 1941, it wasn't an either-or choice for Germany. I think it was actually possible for Hitler to invade the USSR in such a fashion that, if Barbarossa failed, the German army could sort of stop, start backing up, and politely leaving while closing the door behind them. That is to say, the logic that causes the conclusion that the Soviet Union would not destroy Germany might just hold even after an abortive invasion, provided that the invasion was not so horrific that Stalin would literally have no choice but to finish the Nazis once and for all.

Of course, this would require that Hitler not be a genocidal maniac bent on racial annihilation using any flimsy excuse. But still, from a purely theoretical discussion, a Barbarossa that planned to attempt war termination in case of failure made more sense than a Barbarossa that did not, (ie, the historical case).

[TheMarcksPlan]

The data is from Global Logistics and Strategy, 1940-1943, appendices A-4 and E. https://history.army.mil/html/books/001 ... ub_1-5.pdf

This covers only US Army-controlled shipping so the project isn't yet complete. Wanted to present these initial numbers to give some sense of the magnitude of the logistical problem facing the W.Allies if they want to mount a determined defense in Syria/Iraq/Iran.

Important note: "Tons" used in the spreadsheet is Measurement Tons (MT), a US Army logistical unit equal to 40ft3. For some reason, the US Army also calls MT "ship tons." I'll try to say only MT and avoid "ship tons," as that usually has a weight connotation.

Taking all these considerations together, I used 300k MT shipping burden for deploying the average US division to the ME. Seems fair but open to discussion.

---------------------------------------------

At 300k MT per division, the ~14,000 mile journey from NYC to Beirut requires 4.2bn MT-miles of shipping.


I haven't translated LL aid yet

Went back and added an estimate of Soviet LL shipping MT-miles to these calculations, using Appendix D of Global Logistics and Strategy, 1940-1943.

To refresh, the issue is how many divisions the W.Allies could have deployed/supported in the Middle East to oppose a German move from/into Turkey and the Caucasus. As discussed upthread, I only see this happening after defeat of the SU so it's appropriate to consider Allied shipping resources freed from Soviet LL.

Again I have estimated shipping "measurement ton - miles" by estimating the sea routes to the relevant ports:



As you can see, the MT-miles devoted to Soviet LL aid during 1942 could have deployed (but not supplied) <half an American infantry division per month. [calculated as 4.2bn MT-miles needed to ship one inf.div. to ME, as explained in the quoted post]

If we go back and add Soviet LL shipping to my earlier calculations what America could have put in the MidEast, we get:



So if America devoted, from April '42, ALL historical Army shipping to defending the MidEast against Germany, and likewise devoted all OTL Soviet LL shipping, it could deploy (not maintain) ~6 divisions by September '42 and 13-14 divisions by February '43.

Note that ships on the Soviet Far East route were handed to the Soviets from Dec. '41 so counting them is a significant over-estimate.

Supply/maintenance burden can be estimated from the GLS appendices; I've summarized them here. As you can see, monthly supply/maintenance shipping burden is 15-25% of deployment shipping burden, depending on unit type (highest for ID's). Because my estimates are based on inf.divs, we can reduce the free deployment assets by 25% of already-deployed inf.divs. So if U.S. deployed 8 divs to MidEast, maintenance/supply requirements are ~equal to the monthly resources to deploy 2 ID's. As ALL historical Army+SovietLL shipping barely reaches 2 ID's in late '42, 8 divisions is the likely limit of what could have been deployed to the MidEast and supported in combat (this doesn't account for replacements, however).

Another caveat: My estimates are based on divisional slice of the field army. As the MidEast was infrastructure-poor, it would have required a lot of American service troops to man/maintain intra-theater supply lines etc (as was true of British MidEast Command). So again, these estimates are an absolute ceiling on American ability to deploy/maintain forces in the MidEast.

Final caveat: My estimates do not include air forces, whose shipping deployment and supply burden would have been at least a quarter of ground forces, depending on Allied strategy (e.g. are they going to try to bomb Baku? If so, hardly any room for ID's).

-------------------------------------------

As I've observed in multiple posts upthread and elsewhere, British and American high-level decisionmakers did not believe a strong defense of the MidEast was possible against a post-SU German attack through or with Turkey and through the Caucasus/Iran.

Hopkins and Alanbrooke were right of course; the basic shipping math shows it. America could not have deployed a serious force in Iraq/Syria even had it abandoned the Pacific. The SU saved the Middle East from Hitler.

----------------

TMP bookmark: Allied shipping logistics to MidEast in latter 1942

[Peter89]

The data is from Global Logistics and Strategy, 1940-1943, appendices A-4 and E. https://history.army.mil/html/books/001 ... ub_1-5.pdf

Hello TMP,

I think you used the wrong numbers, because the Allies did not have to support or deploy their forces right from America.
For example, fuel, food, clothing and other military stuffs (like cement for constructions) were present in the theatre without any shipping. Not to mention soldiers themselves, which were often coming to this theatre from the colonies like India. The actual shipping needed was much, much less.

Thus, the 14,000nmi distance for cargo and troop deployment is a wrong number.

[TheMarcksPlan]

For example, fuel, food, clothing and other military stuffs (like cement for constructions) were present in the theatre without any shipping. Not to mention soldiers themselves, which were often coming to this theatre from the colonies like India.

Note that my estimate already includes an adjustment to completely remove the fuel shipping burden on account of Abadan. That is definitely far too generous to the Allies for several reasons:

• Intra-theater fuel shipping would be non-zero.
• Abadan supplied the fuel requirements of India, ME, and Australia already. Diverting its output to MidEast Command requires shipping fuel from elsewhere to those places, which requires more shipping.
• It at least can't be assumed that Abadan remains fully operational if LW is operating in-theater.

Despite those caveats, I give the Allies full relief from fuel shipping burden on account of Abadan.

Re food and clothing:

1. Have you heard of the MidEast Supply Center? The general takeaway from its activities is that it narrowly averted famine in the wartime MidEast and reduced the need for shipping to the MidEast. In other words, everything already present in the MidEast was being maximally utilized at this time. Take more food/goods from the locals and you have famine and likely revolt - as you know a very live possibility at this time.

2. You can check the relevance to shipping burden of these items via the appendices to GLS '43-'45. App. A-4 shows that the entire Quartermaster category accounted for only 7% of the initial deployment shipping burden. If food is half of all quartermaster volume (doubtful), that's 3.5%. If you can take 1/3 of your food from near-starving locals, that saves 1% of shipping burden. Of course when they start fighting for the Germans you'll need more than 1% to compensate.

The actual shipping needed was much, much less.

I believe I added the fuel adjustment in response to you pointing out Abadan - I'm happy to adjust for good points like that one. But you need to demonstrate an actual - or at least feasibly possible - surplus in the region to make a convincing point on food or other supplies. The difference between "food" and "extra food" is critical. India was producing ammo, for example, but it didn't have a surplus of ammo over that needed to stop the Japanese (i.e. Britain was still shipping it ammo). Take shells/bullets from India and you're just creating a need to ship to Calcutta instead of Basra/Suez.

Is it feasible that Allies could have squeezed some more food out of the Arabs/Iranians? Sure - maybe more stick and less carrot in this ATL. Would it amount to more than a rounding error on the shipping burden? I can't see how; your quantitative analysis is welcome.

Most importantly, I can't see any good reason to worry I'm missing 1% shipping savings on food or clothes when I haven't even addressed Allied shipping requirements for MidEast air forces yet nor for in-theater logistics/admin troops (combined magnitude >1/4 of estimate so far).

---------------------

General question - I cited direct quotes from Hopkins, Alanbrooke, and other grand strategists explicitly stating that a strong defense of the MidEast - even of holding the Turkish border - would be impossible against a strong German effort. Do you think these guys were wrong? Just want to gauge what your broader point is.

[Peter89]

For example, fuel, food, clothing and other military stuffs (like cement for constructions) were present in the theatre without any shipping. Not to mention soldiers themselves, which were often coming to this theatre from the colonies like India.

Note that my estimate already includes an adjustment to completely remove the fuel shipping burden on account of Abadan.

It's not simply Abadan, there were other refineries in the theatre (Haifa, Tripoli, Bahrein, etc.).

That is definitely far too generous to the Allies for several reasons:

• Intra-theater fuel shipping would be non-zero.

It wasn't zero OTL.

[*]Abadan supplied the fuel requirements of India, ME, and Australia already. Diverting its output to MidEast Command requires shipping fuel from elsewhere to those places, which requires more shipping.

1. Abadan wasn't the only source
2. ME Command received POL in OTL in abundant quantities, besides: refineries were on the standard gauge railways, so even no shipping means that 2-3 refineries' output is accessible

[*]It at least can't be assumed that Abadan remains fully operational if LW is operating in-theater.
[/list]

1. on the original German operational maps, even to consider such an operation required (at the very farthest) to capture the airfields near Mosul, and
2. there was no chance to wage a prolonged bomber campaign against Abadan

Re food and clothing:

1. Have you heard of the MidEast Supply Center? The general takeaway from its activities is that it narrowly averted famine in the wartime MidEast and reduced the need for shipping to the MidEast. In other words, everything already present in the MidEast was being maximally utilized at this time. Take more food/goods from the locals and you have famine and likely revolt - as you know a very live possibility at this time.

Yes, yes, I am familiar with the Allied measures to squeeze out the most food and reduce the shipping to the region.

However:
1. Turkey, by far the biggest food producer in the region, was never under the control of the said organization
2. Extra food sources could be found in, for example, South and East Africa
3. There is a difference between a prolonged campaign and a short campaign. In a short campaign, stocks could be used, which were built up by both the British and the Turks since the beginning of the war. In a prolonged campaign: 1. the shipping situation of the Allies improved steadily, 2. alternative channels of food supply could be used

2. You can check the relevance to shipping burden of these items via the appendices to GLS '43-'45. App. A-4 shows that the entire Quartermaster category accounted for only 7% of the initial deployment shipping burden. If food is half of all quartermaster volume (doubtful), that's 3.5%. If you can take 1/3 of your food from near-starving locals, that saves 1% of shipping burden. Of course when they start fighting for the Germans you'll need more than 1% to compensate.

Probably this is the misunderstanding. You are checking the numbers for A-4, but that doesn't cover the maintenance of the units. Maintenance is in A-5. Also I don't know if we can use these numbers for the Middle East, because the numbers are naturally different than those in France. Not to mention that these numbers are not necessarily valid for every single Allied unit, but an average.

In any case, the total daily requirement of a person is 30.3 kg, of which 15.1kg is POL, 3.25kg is rationing, 3.3kg engineering material. In other words, about half or two thirds of the maintenance requirements could be found in-theatre. (Btw this number includes AF requirements.)

But again; it doesn't make any sense, because there is no such thing as an average day for an average soldier, an these numbers are also irrelevant when the troops sitting idly by or when engaged in heavy fighting.

I believe I added the fuel adjustment in response to you pointing out Abadan - I'm happy to adjust for good points like that one. But you need to demonstrate an actual - or at least feasibly possible - surplus in the region to make a convincing point on food or other supplies. The difference between "food" and "extra food" is critical. India was producing ammo, for example, but it didn't have a surplus of ammo over that needed to stop the Japanese (i.e. Britain was still shipping it ammo). Take shells/bullets from India and you're just creating a need to ship to Calcutta instead of Basra/Suez.

Exactly, and this is why the complexity of this matter is well beyond the scope of my knowledge, because the British Empire stretched across the whole planet, and with her allies and the neutrals it probably covered an area beyond my understanding. I simply don't know, for example, that the Portuguese were able to support the British troops with food, or not? Were the Belgians a liability food-wise, or surplus producers? Where were the food stores located in the colonial system, and what kind and what amount of food they held? How about South America?
Again, I don't know, but I know for sure is that the method to calculate the distance between the US East coast and the Persian Corridor's LL ports for this accessment is simply not a realistic approach.

General question - I cited direct quotes from Hopkins, Alanbrooke, and other grand strategists explicitly stating that a strong defense of the MidEast - even of holding the Turkish border - would be impossible against a strong German effort. Do you think these guys were wrong? Just want to gauge what your broader point is.

My broader point is this: the Germans planned Operation Gertrude OTL, and I think the original plan, that called for a short, sharp campaign against Turkey, might succeed, at least in capturing the large stockpiles of chrome ore on the western part of the country.

A sustained effort, however, is entirely different. The British started to build up the logistical foundations in 1939, and increased the logistical base in Suez from 9 divisions to 23 divisions by March 1942, and the corresponding divisional slice from 25,000 to 35,000. Also, the British policy of spinning a web around the Axis-held Europe was underway, and the gradual buildup of forces continued from 1940 until Torch. The last colonial commitment was at Madagascar, which also diverted forces and other resources. We simply cannot know, or at least I can't know what were the British capable of in late 1942 or early 1943.

The rest is mostly dependant of your ATL about a defeated SU, which I don't want to comment. Such a huge alteration would definately affect other theatres. Without going into the details, extra German gains against the SU would mean less success in other theatres, thus, freeing up more Allied resources would be possible.

Long story short, I simply don't think that there could be sensible calculations made for a hypothetical, prolonged front in Turkey.

[TheMarcksPlan]

You are checking the numbers for A-4, but that doesn't cover the maintenance of the units.

My spreadsheet only addresses deployment.

You're right that fuel is a bigger part of maintenance than of deployment; I should have applied the "Fuel Adjustment" to maintenance as I did with deployment in my rough estimate upthread. When I add maintenance to the spreadsheet I'll remember that.

But again: even with ALL Army and Soviet LL shipping devoted to the MidEast, US can deploy only ~5 divisions to the MidEast by September '42 (rounding up from 4.4 to give you room to push the Arabs into famine - happened to the Bengalis so it's not beyond the British Empire to do so). Even were maintenance air forces shipping 100% free, that's not enough to stop the smallest German army.

Per A-5, btw, food was 11-13% of maintenance requirements.

Plus the US can't devote ALL Army shipping to the MidEast anyway. Most went to the Pacific in '42; if anything more goes to the Pacific if SU goes down.

this is why the complexity of this matter is well beyond the scope of my knowledge...We simply cannot know, or at least I can't know what were the British capable of in late 1942 or early 1943.

You're plenty smart and have sufficient data to know whether Allies could have fielded, say, 20 more divisions in the Middle East in late '42. It's a simple matter of ships and distance. You're invoking uncertainty on the margins to avoid seeing the bigger picture. Even if all food and fuel were sourced in-theater, it doesn't get the Allies anywhere close to 20 more divisions in the MidEast in late '42, not even if they stop defending India and Australia and abandon Torch and Bolero.

Beyond the simple math, we have contemporaries like Hopkins and Alanbrooke answering the question for us.

the Germans planned Operation Gertrude OTL

Because I'm not very interested in Gertrude, and meant to start a separate thread, can we clarify a specific question?

If a post-SU Turkey allows Germany passage through Anatolia or joins the Axis - i.e. the fighting starts at the Turkish border - do you find it plausible that the Allies could have held Syria, Palestine, and Iraq?