Antebellum Attorney General with foreign entities as clients?

Seth Barrett Tillman's picture

The antebellum Attorney General was allowed to have private clients. Does anyone know of any cases where the AG (in a private capacity) represented (in the Supreme Court or any U.S. court of record) a foreign state, foreign government instrumentality, foreign government agency, foreign government-affiliated entity (including a foreign government-affiliated commercial entity), or a foreign (civilian or military) government official, officer, or employee (on behalf of that foreign government)?

This query is for a future research paper, but it may also be useful towards an amicus brief in a matter currently before the courts. 

Thank you.