Here are some people with first world problems.
Why Madonna has decided to go to war with Marine Le Pen is anyone's guess. Le Pen is largely irrelevant, and recently polled a whopping 17% of the vote in the last French election. She is a right-wing reactionary, softened a bit so that she can step away from the shadow of her crazy father.
France is never going to go follow Le Pen's way of thinking; Americans simply do not understand the politics of other countries. She is too reactionary and extreme. The idea of depicting her as a Nazi is an extremely biting piece of commentary on the part of Madonna.
To the French, this is a matter of associating her with Vichy, and that's why the analogy is all the more insulting. Le Pen and her ilk would have likely been a willing group of participants in the Vichy regime, all the more so because of her and her father's anti-immigrant policies. Vichy was actually a broadly popular movement, opposed almost entirely by the communists and by the free French under De Gaulle and not so much from within. Those who supported it were, amongst others, the ideological fathers and grandfathers of those who support Le Pen right now. Don't believe the myth of French Resistance to the Nazis; there is considerable evidence that collaboration was enthusiastically carried out, particularly when it came to the deportation of French Jews.
This is the raw element of Madonna's insult--the world knows that Le Pen has fascist tendencies, given her father's policies and given the party that she leads. But, make no mistake about it--Le Pen is not popular enough in France to attain much of anything other than gadfly status.
Her American equivalent is, well, Sarah Palin, but with a more famous daddy, and from a much richer suburb. One should not make the crazy mistake of putting a swastika on Palin's head.
And Madonna is the voice of reason here? Please.