Definition & Meaning of "[catch] a Tartar"

What is the origin of the idiom "catch a Tartar" and when to use it?

The idiom "catch a Tartar" has its origins in the 18th-century British Navy. Tartar was used to describe the people from the Tartary region, who were thought to be fierce and difficult to capture as prisoners. Figuratively, the phrase means to unexpectedly find oneself in a challenging or difficult situation or to deal with someone who is unexpectedly formidable or troublesome.