In this interview, movie production designer William Stout explains his brief work on A Princess of Mars, which never came to fruition:
And before I forget, in regards to John Carter of Mars — it’s already been made into a movie; a really successful one. So why do we need to make another? That film’s called Return of the Jedi. Princess Leia is dressed as Deja Thoris throughout the film; you’ve got Martian fliers as ERB described them; the main characters sword fight throughout the movie. If you look at it, it’s the essence of John Carter. So if you make a John Carter movie, your audience, who are mostly unaware of the Burroughs books, is going to think you’re ripping off a Star Wars film.
This story illustrates why Hollywood adaptations often fall flat:
So I’m happily humming away on this and from the other room I hear McTiernan say, “Virginia. Does John Carter have to be from Virginia? Why can’t he be from Alaska? Alaska’s much more butch — and we wouldn’t have to deal with those touchy race issues.” I set down the pencil and walk into the next room and say, “John, John. There are really great reasons why John Carter is from Virginia. He was a Captain in the Civil War, but he fought on the wrong side — the South. And he lost. He didn’t own slaves; he was a warrior his entire life. This was a very personal crisis. He was unsuccessful in the defense of his culture. He didn’t know how to deal with it, so he did what a lot of people do when they’re faced with failure. He tried to escape. He went West, where, while trying to just be alone and mine for gold, he’s engulfed in another warrior situation. Americans there are fighting the Indians. Then, he ends up on Mars in the midst of a huge, worldwide Civil War. He is back to Square One but now he’s in a world he was born for. The more he tries to run away from himself the more he finds he has to confront himself. So you have this incredibly rich character, history and past to deal with, which, if he’s from Alaska, you completely lose.” That was my pitch to keep John Carter a Virginian captain in the Confederacy.