Until WWII, the US population generally favored isolationism and were very reluctant to get involved in "Europe's wars". The attack on Pearl Harbor instantly showed Americans that we were no longer insulated from the world.

"During the war, over 16 million Americans served in the United States Armed Forces, with 405,399 killed in action and 671,278 wounded. There were also 130,201 American prisoners of war, of whom 116,129 returned home after the war." https://en.wikipedia.org/wiki/Military_history_of_the_United...

Soldiers returned home with stories of what they had seen, including horrors of the death camps in Europe and atrocities in the Pacific. This deeply affected Americans. I was born decades after it ended, but growing up it seemed everyone older than me had been affected by it.

Also, the modern media age was in full swing. Huge amounts of footage had been filmed during the war, and there was an oversupply of military hardware that needed blowing up. These made WWII films easy to splice together.

The US was operating a massive program of denazification in Germany and demilitarization in Japan. This was combined with economic rebuilding with the goal of establishing the type of peacetime prosperity that people wouldn't want to give up for fighting.

Why Nazis specifically? Many Americans saw what happened to the modern hardworking Protestant society that was Germany and thought "Oh so this is what it looks like when white people become drug-fueled psycho nationalists" and then quickly "Dear God, please not here."

Oh goodness, there were 4.7 million US soldiers in the first world war - out of a US population of 102 million at the time. Surely that must be major?

We entered WWI late in the game and "only" suffered 53k combat deaths. WWI was huge for the major combatants of France, Germany, Russia, and Austria-Hungary, each of whom lost over a million in combat, plus the British empire which lost just under a million between England and all her subjects. To put it in context, more Canadians died in combat in WWI than Americans, and Canada at the time was much less populated than the US, even more so than today. Source: https://en.wikipedia.org/wiki/World_War_I_casualties

So, yeah, we don't tend to think of WWI as much as being one of the major wars we were involved in. The major wars we tend to think about in our cultural consciousness are the Revolutionary War, Civil War, WWII, Vietnam War, and then because of the recency bias, the "global war on terror" in Iraq/Afghanistan. WWI is covered in history classes of course, but primarily from the western front perspective, which the US didn't get involved in until the war was almost won.

The US reacted to the end of the first world war by retreating from global affairs. They didn't even join the league of nations their president was instrumental in creating. WWI was terrible, but it simply did not result in the drastic societal changes that WWII caused.

WWII was the start of a new world order with the USA at the forefront.

Great comment, but aren't you overlooking WWI? Phillipines? etc. There was even an anti-imperialist movement in the US before WWI.

WWII was the last time the US "won" a war, so it gets more attention.

Damn, you're right. WW1 was certainly a major international conflict. Scratch that bit.

It does offer a useful comparison though. In WW1 there were no cartoonishly evil baddies, just a bunch of pointless deaths. It didn't devastate a civilian population, either - nobody got to feel like a hero, there were no joyful liberations. WW2 was a righteous war (that also happened to be an economic goldmine). That permanently shifted American culture (and killed isolationism stone dead). So Nazis became THE enemy - the Lucifer to America's new God complex.

The Germans were cast as, if anything, even more evil characters in the WW1-era propaganda than they were in WW2. A series of atrocities in the opening phase of the war while the German armies were marching through Belgium were widely reported and inflated into stories of raping nuns and bayonetting babies.

In contrast, the full scale of the horrors of the Nazi regime were not widely known until the final days of WW2.