Did those people become unemployed? (Not because of that they didn't. There was a Great Depression and a few wars that could've caused it.)
They mostly stopped working in those fields because everyone hates farming and mining and quits the first chance they get.
Here's recent evidence from Canada, Japan and Spain showing automation caused employment increases:
https://pubsonline.informs.org/doi/10.1287/mnsc.2020.3812
> Did those people become unemployed?
Either unemployed or forced to work in even less desirable places, yes.
> They mostly stopped working in those fields because everyone hates farming and mining
https://en.wikipedia.org/wiki/1984%E2%80%931985_United_Kingd...
No matter how hard the work conditions are, people don't usually accept its disappearance.
Automatization reducing work can actually be a good thing, as it is the reason why we can have vacations, retirement and long studies: because the society's need for work is lower than before.