Quantitative research on demographic measurables and combat effectiveness?

[TheMarcksPlan]

I think one's purpose should be inch closer to practical truths rather than statistical/theoretical constructions of no practical value that helps advance one's career.

Well that's a recommendation not to read about WW2 and certainly not to post on AHF. I deal plenty with practical truths in my day job; here I'm all about the complete lack of practical value.

IQ is a pretty flawed /atrocious measurement of the intellectual "worth" of a man

Any association between worth and IQ is worthless, nonetheless IQ measures something real in the world that is correlated with various outcomes. https://en.wikipedia.org/wiki/G_factor_ ... l_validity

certainly in say front line combat, it is not a matter of egg heads being the best fighters.

Agreed; that's why I said a rifleman probably wouldn't benefit from IQ over 115 or so. Nonetheless, there is a correlation between general intelligence and discrete battle-related mental faculties like information processing speed. https://en.wikipedia.org/wiki/Three-stratum_theory A soldier with 115 IQ will usually be mentally quicker than one with 90 IQ. He'll usually be better and quicker at, for example, visualizing an enemy system of interlocking defense points.

At the upper levels of the general intelligence distribution the correlation between different mental abilities starts to break down. https://en.wikipedia.org/wiki/G_factor_ ... ng_returns That's a bit of research support for the intuition that guy who's best at deep textual analysis isn't necessarily the guy who's best at quickly sizing up a tactical situation on the battlefield.

A Square Meal, A Culinary History of the Great Depression.

Thanks for the cites. To be clear I'm not disputing that there were nutritional effects of the GD in US - again it's the effect relative to Germany and Britain. The only comparative data I have so far is height, which I'm using as a proxy for nutritional deficit. That Yanks were taller than Brits and Krauts suggests they had better nutrition, which doesn't contradict the fact that Yanks, Brits, and Krauts all had bad nutrition during the GD. US also drafted a smaller portion of its population than UK and especially Germany, so probably maintained higher draft standards.

I think you may be making unwarranted assumptions based upon limited data...skewed by personal experience on a post-Great Depression era dairy farm.

I have zero personal experience of dairy farms, post-GD or not. Grandpa was squarely a Depression-era kid on a dairy farm though. I'm working remotely from his house this week, as he still lives alone in his mid-90's and will insist on shoveling his driveway or other such fraught tasks if one us isn't there (the caretaker is on vacation). I'll ask him more about his childhood diet. Maybe about whether his dumber fellow soldiers seemed better or worse at soldiering. He shipped off to war against Germany but it ended before he landed. Shot over the heads of some disrespectful German prisoners though.

[TheMarcksPlan]

I haven't seen any evidence to show what the delta was between nutritional standards of "American boys" and those of the British Commonwealth and Empire of the time.

He also notes that these figures [infant mortality rates] were 'still considerably higher than the rate in comparable countries such as the United States and Australia.'

Height and IMR are powerful indicators of overall health/nutrition.

Forgot about non-British elements of Imperial forces. I suspect that the vaunted combat effectiveness of Aussie/Kiwi/Canadian units - especially in WW1 - was at least partially related to the better health in settler Dominions, relative to UK.

All three of the books I've recommended include references to the fact that the RN and RAF got to "skim off the cream" of the available recruits each year, leaving the British Army with what was left. I can dig out some page references if you are interested.

If there's more than a passing reference, would be appreciated.

[TheMarcksPlan]

Some examples here would be interesting...[re British vs. American combat effectiveness]

Forgot to respond... One example is a TDI study finding:

1. The Germans and the US were roughly equivalent in combat effectiveness, with the US being within 20 to 30 percent of the Germans (possibly lower). This appears to have been especially true in Italy, although they may have had the same combat effectiveness in the Ardennes. The overall impact of US versus German combat effectiveness is not significant
enough to bias further analysis.
2. The Germans and the UK were within the same order of magnitude of combat effectiveness, with the UK perhaps being somewhat inferior (by 20 to 50 percent). While this may
have had some impact on the results of the battles, it was not a significant enough difference to bias further analysis, especially considering the small number of German versus
UK engagements

http://www.dupuyinstitute.org/pdf/e-4epw1and2final.pdf

A co-author of that study in this thread so I'd recommend addressing objections to him.

[Tom from Cornwall]

If there's more than a passing reference, would be appreciated.

Well it is a dull, drizzly day over here so:

Jonathon Fennell, 'Combat and Morale in the North African Campaign':

[p.98]The expansion of the armed forces and the replacements arising from wastage in battle created a problem for the [British] army. There simply wasn't enough good human material to go around. The majority of the best intakes chose to join either the Royal Air Force or the Royal Navy. [Ref. UK NA WO163/123 Army Report No. 72. Allocation of Manpower in the Army: Statement of WO views on the 22nd Report of the Select Committee on National Expenditure (Session 1940-1941). Memorandum by the WO, 20 October 1941] This left the army with what Brigadier John Rees, the Consultant Psychiatrist to the army, called 'the psychopathic tenth' [Ref. LHCMA Adam 3/13 Narrative Covering Aspects of Work as Adjutant-General, WWII, chapt. 2, Selection of Men and Leaders; Ahrenfeldt, Psychiatry in the British Army in the Second World War of the country's manpower, the least intelligent and often the least ambitious of the recruits.

Fennell goes on to cover studies conducted on various groups of British army recruits in 1941 - 1942 on pp.97 - 101. Some highlights:

[p.98] Overall, he [General Ronald Adam when GOC Northern Command late 1940 - mid-41?] found that 4% of intakes were totally useless for any training as a soldier at all [Ref. UK NA WO 163/50 The Army Council, Selection Tests for the Army, Paper No. AC/P(41) 40, 13 June 1941].

[p.99] Another study, carried out in 1942, found that nine out of ten men who reached a minimum level in intelligence tests were successful in training. Below that minimum intelligence level, four out of five men either failed in training, or were reported as unsatisfactory by their field units. [Ref. UK NA WO 32/11972 Notes on the Use Now being made of Psychologists in the Army, 1942.]

As a result, the British Army set up the Directorate of Selection of Personnel (DSP) in June 1941.

By the second half of 1941, the army was discharging about 1,300 men every month because of diagnosable, and therefore avoidable, psycho-neurotic problems during training [Ref. UK NA WO 32/4726/MAC19 Detection of Psycho-neurosis by Medical Boards, January 1942].

Regards

Tom

[Tom from Cornwall]

One example is a TDI study finding

A co-author of that study in this thread so I'd recommend addressing objections to him.

We've covered that [TDI] ground on a multitude of threads on this forum already so probably best to try to avoid heading off down that rabbit-hole again.

In your original post though you made the statement that:

Most analysts find that Americans were generally more effective than British by war's end, for example.

I was wondering if you could point out any other "analysts" who "found" that?

For that matter, I'm pretty sure that Rich wouldn't claim the TDI "analysis" was expected to be the final statement on the matter!

Regards

Tom

[Richard Anderson]

Thanks for the cites. To be clear I'm not disputing that there were nutritional effects of the GD in US - again it's the effect relative to Germany and Britain. The only comparative data I have so far is height, which I'm using as a proxy for nutritional deficit. That Yanks were taller than Brits and Krauts suggests they had better nutrition, which doesn't contradict the fact that Yanks, Brits, and Krauts all had bad nutrition during the GD. US also drafted a smaller portion of its population than UK and especially Germany, so probably maintained higher draft standards.

Okay, but since I don't know of a study that compares American, British, and Germany draftee physiological data, nor in fact do I know of a good source for German physiological data, I'm not sure we can get beyond "probably" in our analysis.

Nor do I know what the various draft standards were in depth, other than for the U.S. Army (AMEDD wrote a complete book on them), but I do know that draft standards were relaxed as the war progressed, rather than maintained.

I have zero personal experience of dairy farms, post-GD or not. Grandpa was squarely a Depression-era kid on a dairy farm though. I'm working remotely from his house this week, as he still lives alone in his mid-90's and will insist on shoveling his driveway or other such fraught tasks if one us isn't there (the caretaker is on vacation). I'll ask him more about his childhood diet. Maybe about whether his dumber fellow soldiers seemed better or worse at soldiering. He shipped off to war against Germany but it ended before he landed. Shot over the heads of some disrespectful German prisoners though.

Sorry, my fault for not reading clearly...and for being the first to introduce the anecdotal fallacy to the argument. Just to illustrate the problem with that particularly insidious fallacy, I just realized my example falls down when looking at my three sons, who are all shorter than I am by 1 to 4 inches.

Anecdotally again , that generation did trend towards being some independent mo-fos. At 74 my Dad insisted on not paying to have the bonus room in their new house finished, because he thought he could drywall and paint it himself, so he taught himself how to drywall and it turned out as good as the job in the rest of the house.

[TheMarcksPlan]

Well it is a dull, drizzly day over here so:

Jonathon Fennell, 'Combat and Morale in the North African Campaign':

Dull and drizzly in England? Shocking. Here in Wisconsin it's -10C and at least a half-foot of snow arrives tonight.

Thanks for the excerpts; I've accessed a copy. Nobody does intellectual elitism like the English:

‘armoured divisions subjected to the stress of active warfare
could [not] afford the risk of retaining hard-working and pleasant dullards who
were slower than the average man to learn what was required of them’

General impression is that the book reinforces that British Army valued intelligence and other personal attributes to a great degree - even outside the officer corps - and learned to devote substantial resources to sussing them out.

I don't know of a study that compares American, British, and Germany draftee physiological data, nor in fact do I know of a good source for German physiological data, I'm not sure we can get beyond "probably" in our analysis.

We won't be able to have any decent quantitative picture but the the logic of nutrition ---> intelligence/health/fitness ---> combat effectiveness seems ineluctable at least regarding ordinal effects.

For a hypothetical research agenda, had someone the time/resources, perhaps certain "natural experiments" could be applied to test for significance. German units' personnel were tied to geographic regions, for example, so if we wanted to test the hypothesis that the GD had bigger effects on non-rural populations one might compare combat effectiveness scores across Wehrkreisse according to their urban/rural composition. Come to think of it, the 1915-20 famine effects would have been markedly greater in more urban districts due to the peasantry having husbanded food during WW1 and its immediate aftermath. Of course the educational levels of urban vs. rural districts would introduce a big confounding variable for which control would be necessary.

Nor do I know what the various draft standards were in depth, other than for the U.S. Army (AMEDD wrote a complete book on them), but I do know that draft standards were relaxed as the war progressed, rather than maintained.

From Fennell's Combat and Morale in the North African Campaign we have evidence that the British had to relax standards even pre-war:

By the late 1930s, men who could scarcely
read or write were being enlisted into the army in an attempt to maintain
numbers.

...whereas US Army seems to have rejected illiterates even during the war.

that generation did trend towards being some independent mo-fos. At 74 my Dad insisted

Haha sounds about right. Once when home from school over the summer, I was sent on emergency trip to Wisconsin because Grandpa - then pushing 80 - planned to resurface his massive driveway by hand. There was a note of resentment in his usually happy greeting. Nowadays the task is to invent new reasons his car has to "stay in the shop" and/or that it's not safe to drive during COVID (Wisconsin inexplicably renews driver's licenses at 8 year intervals, even for 90-somethings). His kids are still afraid of the alternative conversation.

[TheMarcksPlan]

While we're at it, another meta-point/question about combat effectiveness scores...

Did TDI or others ever consider adjusting combat scores for inter-period comparison based on intra-period variance? I'd guess we'd face another practically insuperable data problem but the analytical point still seems fruitful from an ordinal perspective.

Basic insight is that the more mechanized and 3D battlefields of WW2 and later would produce more variance in combat scores than would, e.g., the WW1 battlefield, even holding constant some abstract notion of combat ability. The most anomalous combat effectiveness scores come from WW2 and later - German/Israeli excellence, Italian/Arab failures.

For exemplar inter-period comparison, consider the WW2 Heer vs. WW1. Dupuy finds that the Germans increased their scores relative to Wallies in WW2 (but declined relative to Russians). Might the relative German improvement vs. West disappear when adjusting for intra-period variance in WW1 and WW2? Likewise, might we underestimate the impact of Soviet educational improvements by comparing RKKA to Czarist armies by nominal relative scores?

This makes further sense if one believes, as do I, that irrational fanaticism like Nazism and prevailing IJA doctrine probably undercut combat effectiveness. The Japanese were better when, for example, Kuribayashi deviated from doctrine at Iwo; Halder's Nazi-tinged focus on willpower over logistics undercut Barbarossa.

[Richard Anderson]

We won't be able to have any decent quantitative picture but the the logic of nutrition ---> intelligence/health/fitness ---> combat effectiveness seems ineluctable at least regarding ordinal effects.

Given that health and fitness are requirements for any kind of work and that the problems with shuffling lower-scoring individuals to the infantry are well documented, it is probable it was a factor in combat effectiveness. So were training, leadership, logistics, command and control, and experience.

From Fennell's Combat and Morale in the North African Campaign we have evidence that the British had to relax standards even pre-war:

...whereas US Army seems to have rejected illiterates even during the war.

Before the war, 3.8% of all draftees (a different source says 3.6%, but over a different period) were rejected due to "educational deficiency". They thus raised the standard on 1 May 1941 and the cut-off point became, for better or worse, completion of "four years in an American grammar school", at least until 1 April 1942. However, IIRC it was 1943-1944 that the last 40,000 functional illiterates were separated in the Army. Eventually, 14% of all draftees were rejected due to mental or educational deficiency. The note to the entry reads "Includes (1) registrants with more than one disqualifying defect who were rejected for educational deficiency before 1 June 1943; (2) registrants rejected for failure to meet minimum intelligence standards, beginning on 1 June 1943; and (3) morons, imbeciles, and idiots rejected November 1940-July 1945."

His kids are still afraid of the alternative conversation.

I'd be happy with any conversation with my Dad, alternative or otherwise.

[Richard Anderson]

While we're at it, another meta-point/question about combat effectiveness scores...

Did TDI or others ever consider adjusting combat scores for inter-period comparison based on intra-period variance? I'd guess we'd face another practically insuperable data problem but the analytical point still seems fruitful from an ordinal perspective.

No...if I understand correctly what you are driving at.

Basic insight is that the more mechanized and 3D battlefields of WW2 and later would produce more variance in combat scores than would, e.g., the WW1 battlefield, even holding constant some abstract notion of combat ability. The most anomalous combat effectiveness scores come from WW2 and later - German/Israeli excellence, Italian/Arab failures.

For exemplar inter-period comparison, consider the WW2 Heer vs. WW1. Dupuy finds that the Germans increased their scores relative to Wallies in WW2 (but declined relative to Russians). Might the relative German improvement vs. West disappear when adjusting for intra-period variance in WW1 and WW2? Likewise, might we underestimate the impact of Soviet educational improvements by comparing RKKA to Czarist armies by nominal relative scores?

I don't recall anything that looked specifically at that.

This makes further sense if one believes, as do I, that irrational fanaticism like Nazism and prevailing IJA doctrine probably undercut combat effectiveness. The Japanese were better when, for example, Kuribayashi deviated from doctrine at Iwo; Halder's Nazi-tinged focus on willpower over logistics undercut Barbarossa.

I would not be so sure about that. The Nazi's were extremely adept at simple propaganda designed to motivate the troops through a combination of disciplinary threats and exhortations regarding the privations families were going through because the Wehrmacht could not close the deal. Linking that motivation to a deadly efficient tactical doctrine and an efficient staff system is a large part of what made the Germans so effective. The defects in Japanese doctrine were also balanced to a degree by the regimes ability to motivate the average Japanese soldier and sailor.

[TheMarcksPlan]

I would not be so sure about that. The Nazi's were extremely adept at simple propaganda designed to motivate the troops through a combination of disciplinary threats and exhortations regarding the privations families were going through because the Wehrmacht could not close the deal.

What's the scholarly evidence that this provided any real motivation to German troops? On the other hand we have good scholarship arguing that the German army was particularly combat-motivated by primary group comradeship (e.g. Cohesion and Disintegration in the Wehrmacht in World War II. More recent U.S. Army studies suggest a more central role for comradeship than even for the U.S. Army. https://apps.dtic.mil/dtic/tr/fulltext/u2/a301424.pdf

The LW is generally considered more Nazi than was the Heer - even by Hitler - yet IMO there's more signs of shirking in the latter-war LW than in the Heer.

The biggest Nazi-caused military effectiveness delta was the ruthless suppression of the left, who in any remotely sane society would have undercut German commitment to immolation in a pointless war and ended it sooner (a la WW1).

Aside for others: because we are touching on sensitive matters, I must emphasize the structure of what I'm saying:

• I question to what real extent German soldiers fought in battle for Nazi-inspired reasons.
• I do not question - largely accept - that many German soldiers committed war crimes for Nazi-ish reasons outside of battle
• My hypothesis is that Nazism made Germans worse soldiers - militarily and morally.

if I understand correctly what you are driving at.

A loose analogy is baseball analysis. Players like Carl Yastrzemski and Honus Wagner from lower-scoring eras are underrated compared to 1930's and '90's players (Hack Wilson, Sammy Sosa) if we don't adjust for scoring environment. Properly adjusted, Yaz's 1967 is arguably one of the top 5 last century while none of Sosa's/Wilson's seasons crack the top 100. https://www.baseball-reference.com/lead ... ason.shtml

WW1 Heer is like a deadball-era star whose headline stats underwhelm compared to later eras but whose stats are truly outstanding in proper context.

[Richard Anderson]

What's the scholarly evidence that this provided any real motivation to German troops? On the other hand we have good scholarship arguing that the German army was particularly combat-motivated by primary group comradeship (e.g. Cohesion and Disintegration in the Wehrmacht in World War II. More recent U.S. Army studies suggest a more central role for comradeship than even for the U.S. Army. https://apps.dtic.mil/dtic/tr/fulltext/u2/a301424.pdf

Bartov, although he isn't fashionable anymore it seems, covers the influence of propaganda. Your own source - it isn't a "U.S. Army study" BTW, it's a thesis presented to the USAF Air University - touches on some of the issues, see pp. 24-27 and 32-33. Another source would be Stephen G. Fritz's, ""We are Trying... to Change the Face of the World"--Ideology and Motivation in the Wehrmacht on the Eastern Front: The View from Below", The Journal of Military History, Vol. 60, No. 4 (Oct., 1996), pp. 683-710. You could also search out some of the literature on "Terrorflieger", "Kindermörder", "Luftgangster", and other similar propaganda terms, which appeared frequently in PWI during wartime, and then postwar in German memoirs.

The massive use of propaganda by the Nazi regime to influence the troops is covered by Daniel Uziel in The Propaganda Warriors: The Wehrmacht and the Consolidation of the German Home Front, 2008 and online in https://www.yadvashem.org/odot_pdf/Micr ... 202021.pdf, although the latter more addresses the antisemitic propaganda campaign within the Wehrmacht.

The LW is generally considered more Nazi than was the Heer - even by Hitler - yet IMO there's more signs of shirking in the latter-war LW than in the Heer.

Since I never mentioned anything about shirking that seems to be something of a non sequitur? Or else I am missing the point of your remark entirely?

The biggest Nazi-caused military effectiveness delta was the ruthless suppression of the left, who in any remotely sane society would have undercut German commitment to immolation in a pointless war and ended it sooner (a la WW1).

Again, I am unclear what you are saying or how it is relevant to the topic? I would note though that there could be a case for inferring from its actions that Nazi society was not in fact a remotely sane one.

Aside for others: because we are touching on sensitive matters, I must emphasize the structure of what I'm saying:

• I question to what real extent German soldiers fought in battle for Nazi-inspired reasons.
• I do not question - largely accept - that many German soldiers committed war crimes for Nazi-ish reasons outside of battle
• My hypothesis is that Nazism made Germans worse soldiers - militarily and morally.

WRT your first question, I could be mean and just say "Waffen-SS", but I shan't.
WRT your second question, I said nothing about war crimes, so have no comment.
WRT you statement, well, okay, but I think the simple fact that despite years of war, an extended losing streak in the air, on the ground, and at sea, massive losses, and the repeated destruction of entire armies that otherwise would be expected to have affected cohesion, the best evidence is that German CEV did not change much during the war, until the collapse in late March and during April. While Nazism may have made the German soldier morally worse, I just don't see much evidence for them being militarily worse?

A loose analogy is baseball analysis. Players like Carl Yastrzemski and Honus Wagner from lower-scoring eras are underrated compared to 1930's and '90's players (Hack Wilson, Sammy Sosa) if we don't adjust for scoring environment. Properly adjusted, Yaz's 1967 is arguably one of the top 5 last century while none of Sosa's/Wilson's seasons crack the top 100. https://www.baseball-reference.com/lead ... ason.shtml

I suspect the reference is over the head to many of our international members, but are you including the "juiced" factor as well for players like Sosa?

WW1 Heer is like a deadball-era star whose headline stats underwhelm compared to later eras but whose stats are truly outstanding in proper context.

Possibly? In theory the greatest CEV ever I suspect was Alexander's Macedonians, but it may not be what you are looking for. The problem with CEV crunching in the Great War was there was little,interest in it and creating well-defined daily engagements at division-level to compare with World War II was not easy. The other problem with CEV crunching is that politics meant that funding for any such work in depth was always scarce. Of course, it could get and is worse now, since apparently DOD has decided to stick its head firmly in the base of sand when it comes to combat modeling.

[TheMarcksPlan]

You could also search out some of the literature on "Terrorflieger", "Kindermörder", "Luftgangster", and other similar propaganda terms, which appeared frequently in PWI during wartime, and then postwar in German memoirs.

Since I never mentioned anything about shirking that seems to be something of a non sequitur? Or else I am missing the point of your remark entirely?

I'm compressing the logic; let me expand:

1. LW generally considered to be more Nazi than Heer.
2. If Nazism correlated with combat effectiveness - specifically with soldiers doing their duty despite personal risk (not shirking) - then more Nazi Wehrmacht elements would have shown more excellence in this aspect.
3. I see no evidence confirming the hypothesis in (2). LW had more trouble getting its late-war pilots to aggressively attack bombers (e.g. to close sufficiently when attacking instead of firing from farther away). Heer, by contrast, maintained aggression until very late in the war. Evidence seems to point in direction opposite of (2).

there could be a case for inferring from its actions that Nazi society was not in fact a remotely sane one.

Um that was the point - obviously Nazi Germany was not remotely sane.

I am saying that the paramount "value added" by Nazi regime versus Kaiserreich - in pure military terms - is that Nazi regime made it impossible for left political parties to remind everyone that what they were doing was insane. The WW1 German Left shortened the war, leading to earlier and cheaper German defeat than otherwise would have happened (hope I don't have to differentiate that evaluation from Dolchstosslegende). The WW2 German Left was dead, hiding, or exiled.

WRT your first question, I could be mean and just say "Waffen-SS", but I shan't.

I'm talking about qualitative performance and it seems doubtful that the Waffen-SS was any better than normal Heer. Given their lavish equipment etc., were probably worse. So again this is a case where "More Nazi" and "more combat effective" are not positively correlated - probably the opposite.

the best evidence is that German CEV did not change much during the war, until the collapse in late March and during April. While Nazism may have made the German soldier morally worse, I just don't see much evidence for them being militarily worse?

Again I'm focused on qualitative performance of German land units. Are you saying that the lack of decline during great adversity is attributable to Nazism? That's gotta be somewhat true but again we have to drill down on the concepts we're examining. I've been compressing, mea culpa.

As already said, the suppression of the Left removed factors that otherwise would have caused earlier military degradation/collapse (no good leftists shouting publicly STOP FIGHTING A DOOMED AND EVIL WAR! Just some old reactionary Never Trumpers in secret meetings).

But that's not a change in combat effectiveness, it's the establishment of political conditions for higher overall military effectiveness, including undermining of combat effectiveness by political unrest. [When capture rate is included don't the TDI studies show small but significant decline in German relative scores?]

are you including the "juiced" factor as well for players like Sosa?

Actually I wasn't. Everybody else was probably juiced so the advanced stats that compare performance in contemporary context have that baked in.

When comparing nominal, un-adjusted stats like Sosa's 66 HR vs. Yaz's 44 the juice is definitely relevant. OTOH Yaz's contemporaries were pretty big on amphetamines.

Possibly? In theory the greatest CEV ever

Yeah possibly should be appended to most of what I've said in this thread. Were I publishing something I'd specify epistemic level; typing this while watching the Cotton Bowl I'm less careful.

[stg 44]

I'm familiar with the large corpus on national military effectiveness... Also aware that many militaries (and virtually all modern) use anthropometric/intelligence-testing data for various purposes.

Is there any work correlating anthropometric/IQ data and combat effectiveness at large analytical levels?

The thought crossed my mind because of its potential to explain some WW2 combat effectiveness gradients. Most analysts find that Americans were generally more effective than British by war's end, for example. Systemic features of the U.S. Army surely have a role (e.g. artillery flexibility) but it's probably also relevant that America had higher living and nutritional standards. We were taller and probably had higher IQ as a result (Britain only recently caught up in height).

Similarly, Dupuy concluded- at least as of the time he wrote Genius for War - that the German/Russian combat effectiveness gradient declined in WW2 versus WW1 (at the level of bloody casualties). Surely Soviet educational improvements account for some of that.

I would guess, btw, that Americans were taller and had higher IQ's than the average German soldier, which further emphasizes the German Army's system's role in promoting military excellence.

These effects would be ameliorated by the fact that officers typically came from upper socioeconomic classes that had broadly adequate nutrition on both sides of the pond.

To some of your points, the US had a larger population and one that was far less gutted by WW1, so likely just had more high quality human material as a percentage of the population without even factor in things like nutrition and educational access.

Vis-a-vis German v. Soviet/Russian performance gradient remember that Germany suffered a higher loss to their military age male population than Russia did, lost the war, and then had a spectacularly low birth rate from 1918-1933, lower in total number than in 1870! Since the Soviets were more rural and had a higher birthrate even pre-WW1 and had made huge advances in life expectancy as well as had outlawed abortion they had a lot more young people, to the point that the average age of Russians in 1939 was something like 10 years younger than Germany. If anything the gap was closed due to how badly Germany had suffered in WW1 and after while the Soviets had, despite all of Stalin's atrocities, managed to dramatically improve the overall lot in life of the average person. The literacy program alone was a huge improvement over the Czarist period and had managed to get to nearly western levels of overall literacy among all ages by 1941. So it's no surprise then that the Soviets were able to perform quite a bit better than the Czarist army did vs. Imperial Germany.

As to the performance between the US and Britain...the US had a much larger population and mobilized a lesser part of their population than Britain. Britain also proportionally suffered much higher losses than the US by late 1944 so their manpower was tapped out and they had to make do with manpower quality that was worse than what they had access to in 1939.

Germany performance superiority that Dupuy claims was largely a function of all the paramilitary training the youth got in the Hitler youth before military training and the organizational advantages they had developed based on WW1 experience as they had been planning on a rematch since 1918, while everyone else was more focused on outlawing war and rebuilding.

[TheMarcksPlan]

US had a larger population and one that was far less gutted by WW1, so likely just had more high quality human material as a percentage of the population without even factor in things like nutrition and educational access.

What impact would WW1 have had on quality of men? By the '43 when the Americans are fighting German soldiers, there's very few WW1 soldiers fighting except the officer class.

low birth rate

This relates to quantity of men; hard to see a connection to quality.

The literacy program alone was a huge improvement over the Czarist period and had managed to get to nearly western levels of overall literacy among all ages by 1941. So it's no surprise then that the Soviets were able to perform quite a bit better than the Czarist army did vs. Imperial Germany.

Agreed.

Germany performance superiority that Dupuy claims was largely a function of all the paramilitary training the youth got in the Hitler youth before military training and the organizational advantages they had developed based on WW1 experience as they had been planning on a rematch since 1918, while everyone else was more focused on outlawing war and rebuilding.

Meh I don't buy that kids playing war led by Nazi goons creates any real military excellence. Maybe later when it became more professionalized but German combat effectiveness didn't change much during the war. Most of the 1939-40 Heer had little to no HJ experience.

German combat effectiveness score v. West was nearly as good in WW1 as in WW2. Because WW1 combat scores showed less variance than WW2, I'd argue the WW1 Heer was just as good as WW2. It's hard to show that Nazism added anything to German military capability [aside from willingness to launch WW2 in the first place].