From this question: World War II - Have Historians Envisioned How The Axis Powers Might Have Won? I understand that it is unlikely that Germany with its allies could have won WW2 even if they had decided to do things "differently".

I am wondering what the reasons were for the US getting involved in the European theater. From what I understand, after Japan declared war on the US, Germany also declared war on the US, so one would think that the US didn't have much of an option to just stay out of Europe. Could the US just have ignored the German declaration of war? Even if Germany did have plans of invading the US some time in the future, I am guessing that it would have been unrealistic.

In hindsight if Germany would have lost anyway, what are the main reasons today for saying that it was the right decision for the US to get involved? The only reason that I can think about would be that the US prevented the USSR from taking over all of Europe.

I am sure that most Europeans today are grateful that the US did get involved, but can one make a good argument that the US shouldn't have gotten involved in Europe - like when people today say that the US shouldn't have started the latest Iraq war?


4 Answers 4


Let's clear a major misconception; your question is all about how it can be "right" to go to war, so now I'm morally obliged to counter it with a long, subjective and off-topic rant. Wars are not fought to immediately improve living conditions of a population. Moreover, they are not fought to annihilate the enemy, to wipe them off the planet, or to defend oneself from such fate. The primary reason always was, is, and will be, pure need of confrontation.

War usually does not come as a painful cold-blooded decision, like "too bad, we agree to loose some lives, but we really need the oil to be cheaper" or "... but we really need to live more comfortably" or "... but we really need to free those people from jails and concentration camps". Instead, the war erupts and escalates quite suddenly, without much consideration of future sacrifices and effects.

Humans and some animals (this is male thing in most cases) very much like to risk our own comfort and our own life in a kind of pre-staged situations. Historically, primary example of this is an armed conflict. This need is so strong and prevalent, that even in modern times, when we are educated enough to surely predict that innocent bystanders (even women and children!) would get hurt, from time to time we cannot stop ourselves, which by the way pretty much makes us a bunch of quite murderous beasts, doesn't it? Well, too bad, but to the point.

  • Enter 1939. Germany wanted to confront Poland. They surely could leave them alone and concentrate on defending their land and living there happily. They choose confrontation!
  • Britain and France wanted to confront Germany. They surely could leave them alone and concentrate on defending their land and living... etc.
  • ... etc. (aren't all the following scenarios similar?)
  • Japan wanted to confront United States. They surely could ... etc.
  • Here we are in December 1941, end of the rant, answering your question, please forgive all the rambling:

There are three teams in the world now, Axis, Allied and neutral. One of the Axis have already confronted US, so nevermind US was leaning towards Allies previously, it doesn't really matter. Now US public wants to confront Japan and see them dominated, US commits themselves to Allies. But the leadership, both British and US, is not stupid. They know they can dominate the enemy more effectively (to "win the war" more easily), by playing as a team and by the principle of concentration of power. Why to go one-on-one each in their own theater? They decide to overwhelm the enemy team by concentrating mainly on one region and then on another, etc, until enemy surrenders. Note, the ultimate aim is to dominate the enemy, not to gain land&resources in some theater. On the contrary, they would gain land&resources just as a convenient way to show their enemy "here, see, I've just confronted you and I've dominated you".

Churchill promptly visits Roosevelt for "ARCADIA" conference in December 1941 and they start discussions. Italy is the weakest member of Axis team, can all Allies concentrate on them first? No way. Well then, Japan? Not so good, both Britain and USSR are weak on the Pacific (The World War II Conferences, pp. 17-40). Well then, mainland Europe? Obvious bold yes expected from USSR, but US and Britain are too weak yet (for 1942 and 1943 plans, see Operation Sledgehammer and Operation Roundup respectively, US Army in WW II, pp. 8-10). Roosevelt knows US public is more against Japan but would ok'd anti-German war. Maybe Roosevelt thinks that Germany would dominate USSR, maybe he doesn't - it's irrelevant to my answer. What is relevant, the USSR is fighting Nazi Germany as of now.

Britain eventually proposes to go against Germany outside Europe, to start in North Africa where Germans are weak. Operation Torch ensues, including US landing in Africa. Soviet Union is somewhat disappointed, but they realize that, in terms of all-Allied power concentration, it's the most favorable scenario (North Africa does divert some German resources from USSR theater).

In terms of global "Axis vs Allied" thinking, it doesn't matter for Roosevelt if there is immediate economic US interest in Normandy, or in North Africa, or in Antarctic for that matter. Axis try to dominate Allies, Allies try to dominate Axis, whatever it takes.

The Allied invasion on Sicily follows as a logical consequence, so does the Allied invasion in Normandy.

EDIT: In support of this, count of US Army divisions in active combat. At the very beginning of US invasion on Tunisia 6 divisions, while 4 on Pacific. At the very beginning of US invasion on Philippines (Leyte, October 1944) 17 divisions on Pacific, while more than 30 in Europe. chart

  • Updated, count of US Army divisions in active combat
    – kubanczyk
    Nov 14, 2012 at 16:10
  • 3
    I find the preamble to this answer utterly bizarre and a-historical. In the late 1930s both the UK and US had no desire to go to war. The UK was traumatised by WW1, hence the policy of appeasement ; most Americans probably considered it yet another fratricidal European spat that had nothing to do with them. The decision to go to war had absolutely nothing to do with a testerone-fuelled desire to beat up foreigners, or Churchill would not have been the voice in the wilderness for so long.
    – TheHonRose
    May 13, 2016 at 13:05
  • 1
    The preamble, and this silly bon mot "this is male thing in most cases" detracts from an other wise interesting answer. War (in the context of WW 2) is a form of suasion or goal attainment in the political realm. (One of a number of forms, and a very expensive one). Down voted due to unsupportable assertions. May 13, 2016 at 13:12
  • 1
    I'll also point out that the US re-established the draft in 1940, had been providing aid to Britain before Dec 1941, and had begun large wargames (the Louisiana Maneuvers that exposed a lot of problems in the Army) before Dec 1941. FDR's strategic view that we'd eventually get involved in Europe well predated the attack on Pearl Harbor. Also, American sailors were already dying in the high seas while shipping things to Britain. Your answer (though interesting) does not address the considerable prelude to the declaration of war and Europe First Strategy. May 13, 2016 at 13:21
  • Lastly, on your troop count, Marine Divisions in the Pacific as well as the amount of Naval Forces, not to mention a completely different kind of war in the two theaters. (But your numbers do support Europe First, which was the strategy over Admiral King's strenuous objections ..) May 13, 2016 at 13:23

Two reasons.

  1. Initially it was not evident that Germany would lose war against the USSR. Note that Germany planned to defeat the USSR in 2 weeks and the British government was not optimistic about the fate of the USSR.

  2. Even when the outcome of the war became evident, the US wanted to secure areas of influence in post-WW2 Europe and not to allow all the Europe to fall under Soviet influence. So they had to make the ground landing in Europe in the end of the war so to capture as large territory as possible before the Soviet arrival. The Soviets did not object to that because they had suffered very heavy casualties, and wanted any help that was possible, even at expense of post-WW2 influence.

Other reasons may include:

  • To help the British, a nation with close ties to the US and common culture. The US did not want the British to be defeated

  • To earn positive image worldwide and in Europe in particular given the number of countries occupied by Germany and the number of immigrants from those countries in the US.

  • +1 ing this. However, I don't really agree with the last bullet. That may well have been what happened, but the USA almost never cares enough about foriegn opinion of the USA to let it have a major impact on their foriegn policy. A better bullet along these lines would perhaps turn it around and talk about all the European immigrants from conquered countries who were now USA voters in 1945.
    – T.E.D.
    Nov 5, 2012 at 15:58
  • German immigration into the US had been large in the previous century, and Italian as well, so if pleasing the immigrant population was a factor, it might not have gone the Allies' way.
    – Oldcat
    Jun 30, 2014 at 22:05
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    Where did you get "defeat the USSR in two weeks" from? May 13, 2016 at 11:03

At the start of WW2 US was geopolitically secure with the only potential problems coming from the seas. The world was dominated by the British Empire. However, WW2 changed the American security calculation significantly. First of all, should any power gain dominion over Eurasia, America would find itself in a very vulnerable position. Without US involvement, WW2 could only end two ways:

  1. German victory resulting in takeover of Europe and probably Russia, creating a German empire extending over Eurasia
  2. Russian victory resulting in takeover of Europe by Russia, creating a Russian empire extending over Eurasia

In both instances I assume that China would fall under the influence of the empire.

American involvement was designed to prevent either of these possibilities (basically a divide and conquer strategy). By defeating Germany they created a pro-American camp in Europe to act as a counterbalance to Russia and prevent anybody's dominion over Eurasia. In addition, the collapse of the British Empire created a global vacuum that America was more than willing to exploit to its own advantage.

  • What is the source for existence of US consideration of point 2 ("Russian victory")? At what time they considered it?
    – kubanczyk
    Nov 13, 2012 at 7:48
  • I read it a while ago, but cannot find the reference anymore. I think it's safe to say that not considering the possibility would have been imprudent.
    – SMeznaric
    Nov 14, 2012 at 10:45
  • If, as you say, US aimed to maintain German/Soviet balance in Europe, as of June 1944 they would have switch Lend-Lease to help Germans against Soviet Union, instead of invading Normandy. The invasion on Normandy, so late in the war, indicates that they were very much interested in fighting Germans; so "just conquer" and not "divide and conquer".
    – kubanczyk
    Nov 14, 2012 at 13:16
  • The two are not mutually exclusive. Fighting of Germans with Russians was their way to achieve the goal of splitting Europe into pro-American and Russian camps.
    – SMeznaric
    Nov 14, 2012 at 16:45

The Axis almost certainly couldn't win World War II if the U.S. had intervened in a timely fashion in favor of the others. They Axis MIGHT have won World War II absent such U.S. intervention.

In order of descending importance, here were the impact of potential U.S. contributions.

  1. U.S. Lend-Lease aid to Britain and the Soviet Union. This replaced the material that was lost to/destroyed by Germany in "surprise attacks" early in the war. This put back the Allied forces on an equal material footing with the Axis.

  2. The U.S. fights only Germany's ALLIES; Japan in the Pacific, and maybe Italy in the Mediterranean. Basically, Germany couldn't defeat Britain and the Soviet Union by itself. But it might have won if Japan had conquered China and the Pacific Rim and then stabbed Britain or the Soviet Union in the back (via India and Siberia respectively). American intervention in North Africa (initially directed against the Italians) prevented Germany from overruning Africa, and getting Nigerian oil and Rhodesian chrome. Even if Germany conquers Britain and Russia, the U.S. can "stalemate" her by holding on to South America, Africa and the Pacific Rim (including Japan).

  3. Introduce U.S. ground and air forces into Europe. This ensures the defeat of Germany.

The U.S. had to "play not lose" with at least the first one or two measures listed above. It may not have been necessary to invade Europe. But it made for a "cleaner" post-war order.

  • Speculation or counterfactual? What is this answer all about? The American landings in North Africa were hardly an attack on the Italians May 13, 2016 at 13:16
  • @KorvinStarmast: The Allies killed or captured nearly 300,000 men in North Africa (almost as many as at Stalingrad), and most of these were Italian. Tnen they followed up with an invasion of Sicily and Italy that took several million Italian troops out of the war (through negotiations). "Italy" became a drag on German manpower, coming as it did after Kursk.
    – Tom Au
    May 13, 2016 at 14:02
  • That is because the Germans were few in raw number, but let there be no mistake: the Germans were the ram rod of North Africa (the Axis) as soon as Rommel first set foot there. I agree that the moves to Sicily and Italy were made to knock Italy out of the war. The Soft Underbelly wasn't an American inspired strategy, however. That was Churchill. May 13, 2016 at 14:10

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