1941's actually a pretty good year for femmes formidables, but there's no question that WONDER WOMAN rises to the top of the heap.
Though she was not the first costumed superheroine-- even if one disincluded types like SHEENA and FANTOMAH-- she seems to have been the first coherent "femme formidable" response to Superman. Her original name in William Moulton Marston's proposal was "Suprema," which sounds fairly close to the name of the Siegel-Schuster creation, while two years later Marston remarked upon the resemblance in an issue of THE AMERICAN SCHOLAR:
Not even girls want to be girls so long as our feminine archetype lacks force, strength, and power. Not wanting to be girls, they don't want to be tender, submissive, peace-loving as good women are. Women's strong qualities have become despised because of their weakness. The obvious remedy is to create a feminine character with all the strength of Superman plus all the allure of a good and beautiful woman.
Patently Wonder Woman did allow Marston to elucidate a concept of woman as a "best of all possible female characteristics," allowing her to show evidence of tenderness and what Marston often calls "lovingkindness" even when she's also demonstrating "force, strength and power." This might be a very loose critique of the "tough guy" ethic embodied by the early Superman and most of his imitators. Since Marston was executing an adventure comic book aimed at children, he must have known that most of them would be drawn to the selling-point of amazing feats of power. What distinguishes Marston's hero from most others is that Marston's scripts (quirkily but winningly executed by artist Harry G. Peter) consistently emphasize the need to build a new society of equals following the defeat of the forces of evil.
Marston's conceptualiztion of the Amazon's "dominance-and-submission" society has been the topic of much heated discussion on contemporary message boards. It's easy to poke holes in many of Marston's concepts, but whatever its failings, WONDER WOMAN stands as the first American comic book to evince any sort of philosophical stance. Even comic books and comic strips which critics judge to be superior in terms of script and art (such as Will Eisner's SPIRIT) usually have no philosophical underpinnings as such.
One small hole I can't resist poking myself is that despite all of the Amazon's lip-service to the nobility of submission, Wonder Woman isn't often seen in a submissive posture. Occasionally she's put in bondage and makes some mental comment about enjoying it, but my perception of the emotional appeal of bondage (speaking as an outsider) is that one *can't* get out of it; that one has to make some mental adjustment in order to submit with grace. Largely Wonder Woman doesn't walk her own walk; it's always someone ELSE who has to submit, not her.
That said, Marston's insight into the interdependence of those qualities that Socrates called "valor" and "temperance" is little short of inspired. In an ARCHETYPAL ARCHIVE essay I wrote:
The action-heroine is a better symbol of the Schopenhaurean Will than the male action-hero.
If I had to choose a particular heroine to embody that symbol, no other would be even close.