Just because an evil person derived an idea (that Italian heroism is linked to roman glory), it doesn't automatically mean that the idea is evil. I am sure Mussolini would agree that the sky is blue, for example...

Now, what caused it not to go so well is that he used the idea as an excuse to commit crimes. Which doesn't mean that the idea is criminal itself.

Just because an evil person derived an idea (that Italian heroism is linked to roman glory), it doesn't automatically mean that the idea is evil.

No shit, Sherlock. However, a political idea that fails on worldwide scale is a strong candidate for qualifying as stupid.

Now, what caused it not to go so well is that he used the idea as an excuse to commit crimes.

Genocide is a crime that goes well realizes the malice of its perpetrators on a worldwide scale. So much for your idea of criminal causality.

However, a political idea that fails on worldwide scale is a strong candidate for qualifying as stupid.
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The idea that Italian heritage (including "military heroism") derives from antique roman history has failed on worldwide scale? Care to substantiate?

Have men or nations ever won a fight by boasting about the deeds of their ancestors?

That's totally irrelevant to the original question: that is,
the supposed absence of any Italian war heroes.

absence

shortage