What if the United States never enforced isolationism, and entered World War II in 1939 as an oppose to 1941?
how WW2 would've had play out ?
how WW2 would've had play out ?
IF the USA never enforced Isolationism and maintain a viable military force ...
And convince Congress that they need to create an Armed Force that can fight Two Fronts, one Pacific and one Atlantic and start the buildup after 1936 or 1938...
...
How exactly would the US enter the war in 1939? I believe the US public was rather in favour of isolationism, and the war would be unpopular. You'd need either the Nazis or the Japanese (or Italians?) to do something bad to Americans or America itself to get the American public on the side of the war.
But it'll help Britain and France out in the initial phase of WWII. As noted above, I don't think France would so easily quit with the US on their side, eventually coming to bail them out.
... I believe the US public was rather in favour of isolationism, .
It might help to lead to earlier convoys, improved destroyer production, and more trained troops and pilots.
Capras Prelude to War shows just how pro-isolationist the US was with a Pathe Newsreel from 1939.
You have to be careful with American isolationism, it's easy to misunderstand its nature. From reading those Gallup polls it seems that in 1939 and the first half of 1940 the US public was against American entry generally because they thought Britain and France had things in hand and they didn't see any need to send their boys over to get shot, rather than any affection for Germany or lack of care who won. By 1940-1 they were pleased to be supporting Britain, but still wanted to avoid actual war and hence casualties, unless it seemed to be absolutely necessary - "to prevent the British from collapsing", or something. This was a case of trying to have their cake and eat it, I think!
On that basis it is quite hard to get US entry in 1939 because there simply doesn't seem to be a need for it. You'd need quite a provocation.