En garde!


#1

Isn’t that a French expression on its own?


#2

I think it’s commonly used in English, despite originally being French. Wiktionary for example says it’s borrowed from French. It’s also in the Oxford dictionary as an English phrase.


#3

Yeah, like @mike said it’s from French. You’ll find that English borrows a lot of phrases from other languages, and from French in particular due to the Norman conquest.