A major question, a major discussion topic. Much contention. All kinds of approaches exist for this topic, as well as all kinds of counter arguments to all kinds of propositions.
Many of the arguments are colored either by existing national or social biases, and many of them are colored by propaganda – be it World War II propaganda, be it Cold War propaganda.
But when examined by looking past all these ideological and social biases and historical baggage, one faces a rather unconventional conclusion:
A quick look at the strategic setup, relative war production and technology level of countries seems to suggest that Ww2 could have been won without United States. But it would also take longer and cost more loss of lives.
We have a few major factors:
1 – US help with Lend Lease to allies.
2 – US taking on Japan and preventing them from attacking anyone else.
3 – US as the major part of landings in Northern Africa, Italy and Europe.
When we analyze these, a quick conclusion comes as described below:
1 – US help in Lend Lease to USSR and Britain was considerable. But we must also note that Lend Lease started without US joining the war, on FDR’s initiative, and it would be there until the end of the war even if US did not join the war.
So Lend Lease should not have been a factor in this analysis. But for the sake of a full spectrum analysis, lets assume that Lend Lease was tied to US joining the war, and if US did not join, there would be no Lend Lease.
Lend Lease for USSR was important in non-combat equipment – radios, trucks and similar. US started the war with equipment rather sub par for European front (Tanks, Aircraft especially), and when first batches of these supplies arrived in USSR, they were already unusable in the main front except a few items and they were in small numbers. They were rapidly obsoleted and were relegated to back line duties (reserve, regional back line defense, training) towards 1943 due to speed of technological advancement on both sides. However non-combat aid like trucks, radios are an important factor. These freed up Soviet resources to concentrate on combat vehicle production.
If we consider Lend Lease never happened, these resources would need to be spent by USSR, and hence hamper war machinery production. But when we look at the production numbers, we notice that Soviet war production was multiples ahead of German and Japanese war production. This naturally means that though lack of such supplies like radios and vehicles like trucks would be detrimental, they would not have been critical.
Japan is a special case which maybe we shouldn’t even consider in regard to war production. Japan was far too behind in war production, technology in respect to other combatants. Their heaviest tank would pass in between a light and medium tank in European front, and even at that they were quite, quite few in number to be a factor. Their aircraft carriers are mostly converted from civilian ships during interwar years. They did not have the important critical resources, minerals needed for war production, hampering their already technologically backward equipment. Japanese staff knew this, hence the plan for war against US was a quick strike which would cripple a decent amount of US Navy and therefore hopefully force a quick, favorable peace.
How behind Japan was in regard to war production and technology, we see in 1939 in Khalkin Gol, where Zhukov had devastated a sizable Japanese army during the course of ~4 months.
At the end of the war, the disparage was far greater – Soviets ran over all the elite crack troops Japanese crammed into Manchuria and trusted quite a lot, and they ran over them in just one month. This was the final blow to Japanese war effort and broke the camel’s back, by the way.
2 – US taking on Japan and preventing them from attacking anyone else is an important contribution, but especially in the light of #1, it doesn’t seem to be critical.
If Zhukov was able to destroy a veteran Japanese army in ~4 months in Khalkin Gol, they could easily hold them off with less divisions and resources. Especially considering that the route from NW China/Korea to Soviet heartland passes through never ending Central Asian steppes. Siberia, is not even an option to consider.
Japan would have to cross thousands of kilometers of central Asian steppes in which they would be having to face Soviet armored brigades, who would be at home in these unimpeded plain steppes – these were what Soviet tanks were designed for anyway.
Whereas Japan would not benefit from the lack of resources and infrastructure in these areas. Thousands of kilometers of advance, for nothing, practically. All the while Indian colonial troops in India are still there, and many Chinese factions now encouraged with lessened Japanese forces in China.
That’s assuming they were able to make advances. Khalkin Gol suggests us they wouldn’t be able to.
Even if Japan wisely realized this (and it seems they did, in Khalkin Gol) and refrained from pushing towards USSR, Soviets would still keep divisions across the border even if themselves did not advance – that would force Japan to keep defenses and divisions here, reducing their war effort elsewhere.
On top of that, we don’t see Japan being able to subdue even China before it entered World War II. So even though Japan could easily cripple British presence in SE Asia easily with its Navy (they mostly did that already), it is rather difficult to imagine Japan subduing India – which would turn into another China for Japan.
Therefore, US dealing with Japan definitely helped allies. However it doesn’t seem to be critical to the war’s result. The thing that is certain that war would last even longer in that case, and cost many more lives.
3 – US as the major part of landings in Northern Africa, Italy and Europe is an important bit. Britain, regardless of their stubborn perseverance, was undermanned and under supplied compared to Germany, as evidenced by quick reversal of the early victories they won in North Africa against Italy, after Rommel landed. Rommel had scarce manpower and supplies at his disposal, yet he made good use of what he had, and Britain succeeded in stopping Germans only with amassing of massive resources and manpower in first First Battle of El Alamein. By this time US aid was already flowing in, and the victory came after Second Battle of El Alamein, after US themselves joined. The disparage of manpower and supplies in the lineups are impressive, which makes what Germans achieved in North Africa even more noteworthy.
So we have US as a major factor in Western Front.
But things suddenly take a weird turn after North Africa:
Landings in Western Europe keep getting delayed despite all pressures from Soviets. Churchill is particularly a factor in this. When landings become inevitable, he diverts the landings to Italy, calling it ‘soft underbelly of Axis’. One look at the map of southern Europe easily tells even people with non-military education that there is nothing soft about that location at all – Italy is hilly, rough terrain, and where Italy connects to Europe is even worse – impassable Alps totally clog the north, and beyond Alps there are many more difficult obstacles like Black Forest, or Yugoslavian hilly countryside. The only viable route seems to be towards the West from Northern Italy, from a narrow region towards France. Which could be easily defended by much fewer divisions than the number of divisions it would need to attack.
And not surprisingly, not only the few German forces which took over Italy’s defense from Italian armies defended all of Italy easily and a lot of lives were lost in hilly Italian countryside, but also even at the end of the war the forces in Italy were not able to move out of ‘soft underbelly of Axis’ towards French hinterland, leave aside Germany. If you would like to understand what kind of bloodbath happened in Italy because of Churchill’s political plays, here:
It didn’t end there. Churchill kept working to delay/divert any landing in Western Europe:
The Joint Chiefs of Staff anticipated trouble with Churchill. They wanted to make sure Roosevelt didn’t accept Churchill’s arguments to delay Overlord, the code name for the cross-channel attack, particularly now, when he was on his way to meet Stalin, to whom he had been promising a “second front”, as the Russians referred to it, for well over a year. Roosevelt had caved in to Churchill’s delaying tactics on the invasion before, and now all concerned, from Hopkins to Marshall to Leahy, were worried it might happen again. Secretary of War Henry L. Stimson, fifteen years older than FDR and highly respected by him as an open-minded, patriotic Republican, had had Hopkins to lunch in his office at the Pentagon the day before he left for Tehran expressly to explore how they could stiffen the president’s resolve. “We took up first the question of OVERLORD which we both agreed was the most important problem now before the world and about which we are both anxious owing to the very doubtful attitude of the British Prime Minister. My object was to cheer up Harry and give him my ideas as to how he was to hold the president in line if he could…I have no doubt of the British people doing it. It’s merely that their Prime Minister is balking,” Stimson wrote in his diary.
Churchill’s delaying tactics took the form of pressing for a continued push to divert troops to capture the Dodecanese islands in the Mediterranean and mount diversionary battles in Italy.
The reason why Churchill was doing this, is because he wanted USSR to be destroyed by Germany, or at least “let them bleed each other out”, as the common advocacy was in early years of war among British and US industrialists or Anglo-centrists.
Thus, landings in 1944 came at a point at which Soviets broke German armies and were racing towards Berlin. More from the necessity of preventing a total Soviet takeover of Europe, coupled by the promises FDR gave years ago, than any initiative or lack of malice on the part of Churchill.
So, until 1944 summer, Soviets were practically alone in Europe. By June 1944, Soviets were already positioning for their drive into Germany, as can be seen from the state of Eastern Front at that date:
Just a month after Normandy, Red Army was already pushing into Germany.
When we look at the situation in Western Front, we see Germans not sweating much to stall Allies after Normandy. Normandy and the Bocage around it could be considered bloody battles, with Allies moving inch by inch. By September 1944, we see Allies only coming to German border:
The disproportionate advance of Allies in Western Front in the late stages of the war compared to the advance in Eastern Front after this point is due to German staff trying to prevent a ‘Soviet takeover’ of entire Germany, and preferring an occupation by the ‘other’ Allies. After Hitler became increasingly sidelined, this became a blunt policy, as you would see from the personal stories of relatives of (German) Quorans in regard to the late stages of war, and how many of them were ferried back to West so that they could surrender to the ‘other’ Allies. In contrast, people in Eastern Front were ordered to die where they stood.
In regard to combat balance, we see many disasters in Western Front as well. Operation Market Garden is a special case that demonstrates this, for example. Allied advance in the West definitely took some heat off of Eastern Front, but as can be understood from the situation by the time of landings, Germans did not fear Western Front as they regarded Eastern Front.
The consideration that the possibility of landings tying German forces before invasion comes to mind. Though this indeed tied some German forces, the forces were not anything which could be compared to what was being thrown to Eastern Front, with one notable panzer group being stationed ner Pas de Calais (Hitler’s folly), and most of the preparation taking the form of elaborate fortifications that were called “Atlantic Wall” – prepared mainly by Rommel. But right before the Normandy landings, this region (France, Atlantic Wall) was still considered a ‘holiday’ region by German army, and sons, relatives of notables, party figures were sent there rather than Eastern Front – as one old BBC documentary so bluntly put it. It was the job of the ordinary German to perish in Eastern Front ‘where he stood’.
However, even with lack of US presence in the war, Germany would still need to keep some presence in this Atlantic Wall of theirs. Inevitably so, since British were still in the war, and even though British and Canadians were frustrated in a grand fashion when they attempted a landing in Dieppe Raid to test German defenses in regard to a possible landing, the risk of a potential landing was still there. Therefore they would still have to keep some forces there even if they could reduce them much more. Though, it is questionable how much of the soldiers from Germany’s privileged classes would be shipped to Eastern Front in that case.
Therefore when we look at the presence of US forces in Western Front, we see them delayed by Churchill to almost until the end of the war, and wasted in much bloody, irrelevant and peripheral battles in Italy. Though after landing and adapting to Western Front warfare after a while US forces were the backbone of the effort in Western Front, by the time they started making advance into Germany the war was more or less considered over by many on both sides. After that point it was about who would end up with how much of Europe at the end of the war.
Without US, Britain would still be able to prevent Germany from taking off to the seas. And even if Atlantic War would have been more destructive to Britain and possibly not even won, Britain’s presence as a naval power would not diminish, and hence the risk of invasion of Western Europe would not go away. Though Germans would rightfully conclude that at that point a British invasion would not have much impact, therefore reduce their divisions in the West quite a lot. However when we look at the sizes of the fronts, we see that even at the end of the war by mobilizing even teenagers, Germany would have still been at half strength compared to Soviets even if they moved all their divisions from Western Front to Eastern Front:
Germany – 1944–1945
- ~2,000,000 troops
Germany – 1945
- 1,960,000 troops
USSR – 1945
- 6,410,000 troops
The count of aircraft, tanks and especially guns follow a similar pattern, and especially in the case of guns or artillery, the disparage is greater.
Considering all the above information, it is reasonable to conclude that the war could be won without participation of US, or even Lend Lease, but it would cost much more lives and take much longer, and affect broader segments of world population.