But given that dictators tend to be one sandwich short of a picnic, whatcha gonna do?
There is the perception that ww2 was a "just" war and basically I can't find an argument against that, unlike the slaughter and the carnage of ww1. Maybe if earlier action had been taken the larger losses would have been avoided, but there was an obvious reluctance in view of ww1, to have it repeated all over again.
George Orwell on the Spanish Civil War:
[ ‘Here we are, soldiers of a revolutionary army, defending Democracy against Fascism, fighting a war which is about something, and the detail of our lives is just as sordid and degrading as it could be in prison, let alone in a bourgeois army.’ Many other things reinforced this impression later; for instance, the boredom and animal hunger of trench life, the squalid intrigues over scraps of food, the mean, nagging quarrels which people exhausted by lack of sleep indulge in...(People forget that a soldier anywhere near the front line is usually too hungry, or frightened, or cold, or, above all, too tired to bother about the political origins of the war.)
...War is evil, and it is often the lesser evil]
Erich Maria Remarque's 1929 novel: All Quiet on the Western Front should be compulsory reading in high school.