Why is Napoleon III's regime called "le Second Empire" and not "le Deuxieme Empire"? - yet we refer to the preceding period of French government as "le Deuxieme Republique"

[millais]

Is there a stylistic connotation or some other grammatical reason?

 

[Shig O'nella]

No civilised person speaks French, so the English version of the name is the default.

 

[Pangolin]

It was intended to only be one second long, but due to French labor union strikes lasted several decades longer.