Would a US-involved League of Nations have prevented World War II?

[The world will shine with light in our nightmare]

An explanation for your answer would be appreciated, because this level of political analysis is kind of above my head

[Agonized-Statism]

For World War II, it didn't. As Mussolini said, "the League is very well when sparrows shout, but no good at all when eagles fall out". The League of Nations settled some disputes between smaller nations through mediation and sanctions, but had no teeth against great powers, especially with the rise of fascism.

If the title is a typo and you meant World War I as I'm assuming, it would have run into the same problem.

[The world will shine with light in our nightmare]

For World War II, it didn't. As Mussolini said, "the League is very well when sparrows shout, but no good at all when eagles fall out". The League of Nations settled some disputes between smaller nations through mediation and sanctions, but had no teeth against great powers, especially with the rise of fascism.

If the title is a typo and you meant World War I as I'm assuming, it would have run into the same problem.

No, sorry, the title is what it means. If there was no resistance to Wilson's foreign policy and the US joined the League of Nations, and supported them militarily, would that have mitigated the factors that led to Adolf Hitler's rise?

[Agonized-Statism]

For World War II, it didn't. As Mussolini said, "the League is very well when sparrows shout, but no good at all when eagles fall out". The League of Nations settled some disputes between smaller nations through mediation and sanctions, but had no teeth against great powers, especially with the rise of fascism.

If the title is a typo and you meant World War I as I'm assuming, it would have run into the same problem.

No, sorry, the title is what it means. If there was no resistance to Wilson's foreign policy and the US joined the League of Nations, and supported them militarily, would that have mitigated the factors that led to Adolf Hitler's rise?

Oh, so the question is whether or not US involvement in the League of Nations could have prevented World War II. In that case, still, probably not. You still have the Great Depression to contend with: the countries that turned inward to deal with it still wouldn't be very willing or able to enforce League rulings in the 1930s, including the United States. Nor did autarkic Germany, Italy, or Japan care much about being internationally isolated by the League anyway, so nothing short of war could have stopped them.

[Sir Mohamed]

There's little reason to believe so. Hitler dismissed international organizations and treaties and just terminated them when it didn't serve his intrest. And his rise to power is rooted in factors beyond the control of what a League of Nations could have achieved. The narrative it would have prevented is a myth in my opinion.

[The Mikado]

The moment the League's uselessness became obvious was in 1931 when Japan invaded Manchuria. The League condemned it, Japan responded by withdrawing from the League and...nothing happened.

If the USA had been in the League as well, I see no reason to think these events would've gone differently.

Ditto five years later when Italy invaded Ethiopia despite the League Charter saying that the League would protect the independence and territorial integrity of its members. No one wanted a war over it so the League did nothing.

The League of Nations could do one thing reasonably well: arbitrate disputes between countries that don't REALLY want to fight over the dispute. Their greatest success story was adjudicating whether the Aland Islands should be in Finland or Sweden. Neither Finland nor Sweden had any interest at all in fighting a war over the islands, so handing them over to adjudication was a reasonable situation, and the eventual result (Finland gets the islands but can't make any move to suppress Swedish language or culture) was acceptable to all parties.

These circumstances weren't present with the Manchuria crisis or the later Ethiopia crisis. Japan and Italy WANTED wars.