Your British history is lacking, most of the Cajuns were force settled there from Canada after England won the French-Indian wars.
You're the one who doesn't know your Cajun history. Yes, they were kicked out of Acadie, today's Nova Scotia - many went back to France, found it undesireable, and then settled in Louisiana, which was then under the protection of the Spanish crown. It was a conscious choice to go there.
Ivan