French plan to invade Britain circa 1779 -- Follow-up

Many thanks to you folks who put me on a valid track. Answers I have found, so far, lead to questions.

I have identifed French officials “Sartine” and “Montbarey” as having a plan to invade Hampshire. The plan was completed [by] March 19, 1779.

Who were these two people?

“French officials” is vague. What rank or position in what part of French military or civilian service were they?

Where can I find English-language biographical sketches for these people?