There are times i wonder if WW2 was facists vs facists about who was to run the circus.
Fighting fascists on their own terms will, of course, make you more like them. Just like the Cold War led to the committee of counter-revolutionary - excuse me, anti-American - activities, War on Drugs led to police behaving like a criminal cartel, War on Terror in practice means assassinations and bombings, and so forth. You cannot wield power without yielding to it; you can sit on a throne but it'll be the logic of the throne which dictates your actions, not the other way around.
"Even if we lose this war, we still win, for our spirit will have penetrated our enemies' hearts." --Goebbels
âoeWhoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you.â --Nietzsche
Goebbels was smarter than Nietzsche, at least in this regard; he saw the process as inevitable. An evil regime might be crushed by force of arms, but the spirit it embodies can't be. And of course the same works the other way too, thus for example the Baltic states popped right back into existence as soon as Soviet oppression slipped. Humans aren't really sapient yet; we simply have some of our instincts dictated by memes rather than genes, and the process is unconscious. Becoming fully aware of it is likely the next big step forward, assuming we survive our current troubled childhood.