Which one was more crucial and decisive: United States intervention in WWI, or WWII?

[redlightning]

I want to know what the American public would've thought of no intervention in either campaign during the war with the US staying completely isolated through the whole event.

I guess a completely Red continental Europe, Soviet dominated Africa, and a Japanese colonial empire controlling at least coastal China wouldn't sit well at the end of the whole event.

 

[Aber]

How much difference did 4 corps worth of French infantry make to their ability to hold come May 1918? A lot in fact, as that is the better part of an entire army.

The French averaged more than 2 divisions to a Corps so your comparison is incorrect; the U.S. were <5% of the forces on the western front.

 

[jmc247]

Without intervention in WW2 Germany ends up with an Empire reaching from central Europe through Ukraine and parts of Russia, but falls far short of to the Urals. Western Europe on the continent other then Britain ends up on paper independent, but in reality Germany's bitch.

Without intervention in WW1 Germany ends up with puppet states in the East and in the West Germany's bitch other then perhaps Britain.

 

[Deleted member 1487]

The French averaged more than 2 divisions to a Corps so your comparison is incorrect; the U.S. were <5% of the forces on the western front.

http://www.worldwar1.com/dbc/squarediv.htm

The pre–World War I triangular design was deemed insufficient, lacking enough flexibility, control, and sustainable combat power. Deemphasizing mobility and maneuver, the division was to be bulked up and reorganized to fight prolonged battles in sustained frontal attacks.11 While not totally abandoning mobility, this cornerstone of U.S. Army warfare was sacrificed somewhat in the interest of firepower needed to penetrate German defenses and exploit breakthroughs.12 The commander of the American Expeditionary Force, General John J. Pershing, fixed the division at 979 officers, 27,082 men (about 40,000 all told, including support personnel).

Pershing created this division—which was more than twice the size of its European counterpart—to “achieve a capacity for sustained battle which would ensure that American divisions would not falter short of their objectives as British and French divisions so often had done.

 

[Rex Romanum]

If by intervention you mean proper military intervention, there is no contest. American intercention in WWI pales compared to the numbers, the effort and the effects over the terrain of american intervention in WWII.

Now, if by intervetion you mean something more generic, then there is contest.

Well, the latter, then.

 

[wcv215]

Decisive and crucial are not the same thing.

Decisive is WWI easily. Without American entry Germany might not have launched the offensives that wiped out their reserves, the Allies would not have had access to further funds as their collateral was gone, the Allied soldiers on the Western front wouldn't have had the morale boost of knowing another country was on the way, one which had millions (in theory) of people ready to bolster the faltering lines, one which would lead to their own number not being in harm's way as often. The Germans meanwhile were faced with exactly the opposite: a completely untouched enemy who had bottomless (by comparison at least) money to draw on, an enormous manpower pool which hadn't been worn down by years of war. And it was all coming at them. More than that though, American entry on the Allied side meant the last real economic hope, that the Allies would run out of money, or even that the blockade might end were gone.

Crucial however is far more WWII. Even ignoring soldiers, the equipment, the food, the fuel, the boots, the trains, the trucks, the metal, etc. came from the United States, and without that Allied victory becomes far more doubtful (on the level of OTL virtually impossible). Without the US there is no bombing campaign, no annihilation of German infrastructure, no second front for Germany to throw a disproportionate share of their tanks at. There is no Navy (or at least not one near the size and power) to throw the Japanese back across the Pacific, to island hop to bombing range of Japan itself.

 

[zert]

In my opinion the US was needed/if not at least extremely helpful, in both Wars. Materials, Money, and Men proved pivoting for the Allies.

 

[Johnny Canuck]

Nonsense the US had 4 divisions, each equivalent to a Entente corps in size, in the line in quite sectors during the German offensives and that freed up a lot of French troops for operations at a critical moment. That's also ignoring the huge food, oil, and steel contributions that were made by the US and was paid for by US loans that enabled the Entente to continue the war past 1917. Without that the Entente would have collapsed economically.

In some ways, though, the arrival of the Americans in Europe were a drain on the combat power of the French Army: 84% of artillery, 79% of tanks, and 77% of aircraft used in combat by American forces in Europe were provided to them by the French. Indeed, if the French had not had to equip the Americans, their own army would have been significantly better equipped - Petain on several occasions in 1918 complained that the French army did not have enough equipment because too much was being diverted to the Americans.

 

[Aber]

http://www.worldwar1.com/dbc/squarediv.htm

Even counting US divisions at 2x other countries divisions, still < 5% of the Western Front.

 

[Arnold d.c]

Both were pretty crucial. In WW1, the French army mutinies had just occurred and American reinforcements were useful. Well WW2 is pretty obvious although American intervention was crucial the Soviets could've won the war with lend-lease

 

[pdf27]

Need to be very careful with WW1 - without the prospect of US unsecured loans, the Entente powers would probably not have spent so much in the USA. Similarly, without the prospect of very large numbers of US soldiers they would probably not have been quite so offensively-minded in 1917 - as indeed the Germans wouldn't have been in spring 1918.
The point is that in the war which played out US support was crucial - but a war in which the US isn't going to join will have several critical differences such as most likely no USW, more conservative Entente strategy, etc. The Entente will be shaping their strategy to rely less on the US if it isn't obvious that they will be joining in the war - and so the US becomes less critical. Same thing happens with WW2, just rather more obviously.

 

[Deleted member 1487]

Even counting US divisions at 2x other countries divisions, still < 5% of the Western Front.

Source? And at what time? At certain crucial moments that 5%, if true, was crucial to providing a reserve for the French.

Need to be very careful with WW1 - without the prospect of US unsecured loans, the Entente powers would probably not have spent so much in the USA. Similarly, without the prospect of very large numbers of US soldiers they would probably not have been quite so offensively-minded in 1917 - as indeed the Germans wouldn't have been in spring 1918.
The point is that in the war which played out US support was crucial - but a war in which the US isn't going to join will have several critical differences such as most likely no USW, more conservative Entente strategy, etc. The Entente will be shaping their strategy to rely less on the US if it isn't obvious that they will be joining in the war - and so the US becomes less critical. Same thing happens with WW2, just rather more obviously.

And get the oil, food, and steel that the US provided from where? They wouldn't be able to spend from 1917 on in the US, but then not be able to get those resources elsewhere.

 

[avernite]

IMO 1918 showed the Germans didn't quite have the punch to knock out Britain and France (even if they could punch hard).

However, the morale issues faced by the French and British would have been worsened severely by the lack of US involvement and US supplies to make life easier. And without the US the WAllies might just have done something stupid to try to save Russia (with the USA in, they could think, 'well Russia's out but we got a fresh better version').

So, I expect in WW1 the result would be broadly negotiated peace in the west (maybe partly offsetting the massive gains of Brest-Litovsk?).

In WW2, Barbarossa and on had shown that this was a war with only last-man-standing as a victory condition for Germany and the USSR, and because the Soviets were gonna win 9 times out of 10, that means a more westerly communist-capitalist border (and more dead Russians) but no big change to the outcome of the war.
I kinda assume the USA staying out precludes the war in the Pacific really breaking out.

 

[fastmongrel]

I voted WWI simply because without WWI you dont get WWII or at least you get a totally different WWII. Wilsons about face over the League Of Nations killed any chance it had of being a world policeman preventing a future re match.

 

[Alternator]

I voted WW2, but for a slightly different reason than most given here.

If the United States is clearly, and genuinely (IE, not playing favorites with selling supplies) neutral in WW1, it limits what the British and French can do just because they have less money, so they'll have to conserve supplies more. I expect the Germans will still knock the Soviets out of the war and the British will still probably roll the Ottomans up through the Middle East, but there is nothing that the remaining Entente can do to beat Germany and Austria-Hungary after Russia is knocked out. Too many German troops coming back to the western front, and the Entente is still going to be running lower on supplies - they might not outright lose, but the peace is at least somewhat favorable for the non-Ottoman Central Powers.

Combine that with the gains of Brest-Litovsk and it's an overall win for Germany and maybe Bulgaria, and everyone else comes out worse (Austria-Hungary still faces unrest, France and Britain nominally lost, Russia and Ottomans beaten). As long as the Kaiserreich doesn't push France too hard, this probably just changes the balance of power and ends up well enough.

If the United States remains fully uninvolved in World War 2 that means the Soviet Union has no Lend-Lease to provide supplies while they shift their industrial base east. I suspect the Soviets would still end up bleeding Germany dry and winning that fight, just because Stalin was crazy enough to fully exploit the larger Soviet population, but it would cost far more lives and give the Nazis more time to depopulate eastern Europe.

Japan would still be buying US oil, and wouldn't have to overextend so far. They don't have the manpower to truly conquer China, but they can certainly occupy much of the coast and expand their Co-Prosperity Sphere.

This is a terrible world filled with terrible things, and it is why US involvement was more crucial in World War 2.

 

[Mustache Cash Stash]

If America did not intervene, Britain would have run out of cash (due to lend-lease). The Soviets would have crashed even harder and likely would have surrendered very quickly.

 

[pdf27]

And get the oil, food, and steel that the US provided from where? They wouldn't be able to spend from 1917 on in the US, but then not be able to get those resources elsewhere.

Oil - not a huge amount being used at the time, and they had specifically founded the Anglo-Persian oil company to provide supplies to the RN in wartime.
Food - Canada, Australia and South America.
Steel - they're limited to their own resources, which are not inconsiderable. That's the only one for which there is not a clear alternative source (which requires more shipping, but then again they probably have more - keeping the US out probably requires no USW).

You end up in a situation where operations are a bit more constrained - imports mean that the manpower otherwise required to produce them has to be diverted to the civilian economy, and in WW1 were also used to increase the total production of the war economy. Given the political effects of the unconstrained operations they tried in OTL after the US declaration of war (the Nivelle Offensive and 2nd Ypres/Passchendaele) this may not be such a bad thing - if 2nd Ypres had been limited to the taking of Messines Ridge and the Nivelle offensive cancelled entirely, the Entente powers would have been in a much stronger position in 1918.

This isn't to say that cutting off US imports isn't a bad thing - if it was they wouldn't have accepted them in the first place. What it's saying is that you can't just look at OTL plans and try to implement them in the absence of those imports - the plans would have changed too in order to adapt to the revised supply situation.

 

[LordKalvert]

Source? And at what time? At certain crucial moments that 5%, if true, was crucial to providing a reserve for the French.


And get the oil, food, and steel that the US provided from where? They wouldn't be able to spend from 1917 on in the US, but then not be able to get those resources elsewhere.

The Americans never have more than 2,00,000 men in France- something that Britain alone could have added (she had 1,400,000 in her insanely bloated home army for example)

The supplies would be available- Loans may have been restricted but the British and French had lots of collateral and home assets they could put up.

The British and French home fronts haven't faced anywhere near the drop of living standards as the CPs had faced

Finally, their colonial empires offered a virtually unlimited amount of manpower- either for use at the front or for freeing up men to go to the front

 

[Mikestone8]

Oil - not a huge amount being used at the time, and they had specifically founded the Anglo-Persian oil company to provide supplies to the RN in wartime.

Food - Canada, Australia and South America.

Steel - they're limited to their own resources, which are not inconsiderable. That's the only one for which there is not a clear alternative source (which requires more shipping, but then again they probably have more - keeping the US out probably requires no USW).

Actually it doesn't - only avoiding American ships as far as possible - of which only a few were sunk without warning even OTL.

In any case, the importance of USW is much overrated, since the limited supply of torpedoes meant that even after its introduction, most sinkings still had to be done by "cruiser rules". The rate of sinkings was rising sharply from Dec 1916 - well before its introduction - as more subs were brought into action, and would in all likelihood have continued to rise even without USW.

In addition, switching to alternative sources would in most cases have necessitated far longer voyages. Frex, South America is twice as far away as the US, so only half as many voyages could be made in any given time. The effect would be the same as if half the ships had been sunk - a vastly bigger difference than the U-boats could ever have made, and more than offsetting any difference made by no USW. India and Australia are of course even further away, so the problem there would be even greater.

This, of course, assumes that alternative sources would be available. But see the following from Kathleen Burk Britain, America and the Sinews of War, Ch 5.

"- - the [British] Foreign Office called together an interdepartmental committee on 30 September [1916] to consider how far Britain was dependent on the United States; the statements of the various departments were printed for the Cabinet on 6 November, and the conclusions were alarming. The Ministry of Munitions procured a large percentage of its guns, shells, metals explosives and machine tools from the United States; The Army Department considered that there was no substitute for American supplies of oils and petroleum, nor for that of preserved meat; The Board of trade stated that for cotton, for foodstuffs, for military necessities and for raw materials for industry, the United States was "an absolutely irreplaceable source of supply"; the Board of Agriculture emphasise the dependence of Britain on the United States for grains; and finally the Treasury stated baldly 'Of the £5,000,000 which the Treasury have to find daily for the prosecution of the war, about £2,000,000 has to be found in North America', and added that there was no prospect of any diminution without a radical change in the policies of the Allied War Departments. The Treasury expressed, in its conclusion, the only action possible fort he government; 'The policy of this country toward the USA should be so directed as to not only avoid any form of reprisal or irritation, but also to conciliate and to please' "

Were all these departments misinforming their government?


PS - May I extend my sincere apologies to all "regulars" on this forum who have read this or similar passages on previous threads, with such monotonous regularity that by now they can probably recite it in their sleep? It's always an idea to use the search function when responding to a "hardy perennial" like this..

 

[Mikestone8]

The supplies would be available- Loans may have been restricted but the British and French had lots of collateral and home assets they could put up.

I'm not sure what you mean. The whole point of collateral is that it has to be available for seizure in the event of default, ie within the jurisdiction of the courts - in this case US ones. "Collateral" outside that jurisdiction just isn't collateral.

Finally, their colonial empires offered a virtually unlimited amount of manpower- either for use at the front or for freeing up men to go to the front

The obvious source would seem to be Ireland - by far the nearest "colony". Iirc the Conscription Act was extended to Ireland, but they never used it. I'd love to see the fireworks if they did.