[FredZarguna]

I can't put my finger on my notes at the moment, but I believe James Clerk Maxwell had already fired the first salvos against Newtonian Physics a few years before that. Very close to 1859, it became obvious before Maxwell first published his unified theory of the electromagnetic field that electromagnetic induction was what would later come to be known as Lorentz Invariant and that Newtonian Mechanics was not.

There was even a period before the Special Theory of Relativity when physicists would say "everything obeys Newtonian mechanics, except for electric current."

[Moonman62]

There was even a period before the Special Theory of Relativity when physicists would say “everything obeys Newtonian mechanics, except for electric current.”

...

Yep. A lot of the fundamental work for relativity was already done by Lorentz and Poincare. But Einstein was the only one to come up with the proper reasoning.