I have a little info on HG Wells and The War of The Worlds.

As you might be aware, the British author HG Wells wrote The War of the Worlds in 1897. It’s pretty much the first ‘alien invasion’ story, featuring Martians laying waste to Victorian Britain and it is one of the cornerstones of modern science fiction. At the time it was common for many writers to serialise their works before full publication and The War of the Worlds was no different, being serialised in Pearson’s Magazine from July-December 1897. Pearson’s was a British and then later US periodical [1].

Due to its immediate popularity, copycats and rip-offs popped up very quickly in other magazines. One of the most famous was Fighters from Mars. This was a serialised work in the USA which heavily edited Wells’ original story, cut large sections out and relocated the action to North America. Wells himself was highly critical of this, calling it a “serious infringement of my copyright” and that he felt “bound to protest in the most emphatic way against this most serious manipulation of my work” [2]. It’s clear he was not happy about this, but he does seem open to attributing it to “a terrible mistake” rather than “wickedness” [2].

It is easy to understand Wells’ ire - his work used the story of an alien invasion to critique elements of British society, contemplate evolution and repudiate colonialism. Much of this careful subtext was lost in the Fighters from Mars rip-off. He also would have lost out financially to a considerable degree, so whilst his work was being mutilated and re-hashed it was also being pirated.

Either way, we can infer that this protest from Wells did not amount to much as it did not stop further copyright infringements. Almost immediately and ignoring Wells’ wishes, a sequel to Fighters from Mars, called Edison’s Conquest of Mars followed. This stretched and skewed Wells’ original work even further and reads like a piece of fan-fiction. The narrative, in brief, features Thomas Edison using his various inventions and flying machines to invade Mars and wreak revenge on the Martians for their prior attack on earth [3]. This bombastic tale was a far cry from Wells’ original work, which is widely regarded as a masterpiece of Victorian science fiction. However, Wells seemed either uninterested or unable to stop this further infringement and this ‘unauthorised sequel’ went on to enjoy considerable success in North America.

As an interesting aside, Fighters from Mars and Edison’s Conquest of Mars directly inspired a young Robert H. Goddard (the American rocket pioneer) to take up rocketry and the idea of interplanetary exploration, so perhaps some good came of it! [4].

I don’t have information on the intricacies of Victorian copyright law, although it seems clear to me that the American magazine industry was very happy to ignore whatever rules existed - at least for works created outside of North America. Hopefully this example answers some of your very interesting question OP.

[1] Examples of Pearson’s: https://catalog.hathitrust.org/Record/000495191).

[2] Wells’ letter criticising Fighters from Mars: https://books.google.co.uk/books?id=F8sQEAAAQBAJ&pg=PA300&lpg=PA300&dq=%22Yet+it+is+possible+that+this+affair+is+not+so+much+downright+wickedness+as+a+terrible+mistake%22&source=bl&ots=maFKQFvGPq&sig=ACfU3U0G059ge5VEhA6RPorJVeYRYbjQ4g&hl=en&sa=X&ved=2ahUKEwj2l--D0_3xAhWHXsAKHdK8AaUQ6AEwAHoECAMQAg#v=onepage&q&f=false

[3] Edison’s Conquest of Mars text; https://www.gutenberg.org/files/19141/19141-h/19141-h.htm

[4] Goddard’s inspiration http://ol-web1.us.archive.org:8080/works/OL4998710W/Edison's_conquest_of_Mars