TIL Black Americans were developing the Afro-Futurism/Black Sci-Fi genre of literature as early as the mid-19th century. Titles such as 'Blake' (1859), 'Iola Leroy' (1892), 'Imperium In Imperio (1899)
TIL Black Americans were developing the Afro-Futurism/Black Sci-Fi genre of literature as early as the mid-19th century. Titles such as 'Blake' (1859), 'Iola Leroy' (1892), 'Imperium In Imperio (1899)

Black science fiction - Wikipedia

You might be right about these not being sci-fi, but sci-fi can take place in the period in which it was written. Alternative history plus sci-fi can definitely be a thing. Or writing sci-fi that's supposed to take place in just a few years.
And I addressed that. I wouldn’t even feel comfortable calling said title alt-history.
Do you think a title like the DaVinci Code is sci-fi because it altered history?
These sound like fictional drama/thriller books in a period piece setting to me.
Speculative fiction is generally a better term to avoid quibbling over details. The speculative step is the important defining thing in any case.
You should edit the wikipedia entry then, because it disagrees with you.
"Samuel R. Delany described it as "about as close to an SF-style alternate history novel as you can get.
Further, while it incorporates elements of the fugitive slave narrative, Blake's narrator is also a scientist, whose focus on data collection and research stand in repudiation of the racial science of the day.[10] In fact, this reflects one of Delany's major themes: that Africa and its contributions to science and math were foundational to the Western world.[12]"
Because one author says so does not make it so.
Considering we're talking about the era of the belief in Drapetomania, I'd say a slave revolt followed by an attempt by black people to take over Cuba would be considered sci-fi by a lot of readers.
Edit: Also, sci-fi wasn't really a thing in 1862.