In looking for something else, I discovered there was a sequel to H. G. Well's book War of the Worlds! Well, kinda.
Back in 1898, when War of the Worlds came out, international copyright law was much like the Pirate's Code - more guidelines, really, than law. So, when War came out, various people rewrote it to their own liking, setting it wherever they felt it would be convenient. One of those (highly unauthorized) rewrites was Fighters from Mars, set in and around Boston.
This was such a commercial success that an American astronomer, Garrett P. Serviss, was engaged to write a sequel. The result was Edison's Conquest of Mars. (You can read it here for free or buy a dead-tree book here.) The plot is that Thomas Edison, working on behalf of then-current world leaders, reverse engineers the Martian tech and leads a fleet, first to the Moon and then to Mars.
Herewith are some comments:
1) They wrote shorter in those days - the book is around 65,000 words - but they didn't skimp on story. This was accomplished in part by cutting out description. The Martian Emperor's palace is only described as "ornate in the Martian style." The only named character described is the human slavegirl Aina, and we're just told that she's "lovely."
2) Serviss, the author, expropriates a number of famous scientists of his day. Edison, the protagonist and a man in nearly every scene, is used with permission. The rest, not so much.
3) It is a novel of its time. As Jo Walton said of another book, it was "written before women were invented." Queens and princesses are mentioned, but the only speaking part is that of the slavegirl, and when she goes on a raid with the men, she's "of course not in a combatant capacity." Also, all the foreign heads of state speak perfect English except the Chinese emperor - and he's the only one not to ride in Edison's electric airship.
Having said all of that, Edison's Conquest of Mars is a rip-roaring adventure, and quite entertaining. It's also clearly the precursor to Burrough's Barsoom series, among others. In it's day, Conquest was a very popular book, and inspired a lot of people, including one Robert Goddard.