English speakers use the name Georgia for both the Caucasus country and the U.S. state, but why?

In their native tongue, Georgians refer to themselves as the Kartveli and to their country as Sakartvelo. But the Kartveli have for many centuries been associated with George, the Roman soldier and Christian martyr.

Noreen Malone of Slate blames the British for the two Georgias in a recent column where she traces the history of these placenames.