Who is Colonel Jean-Baptiste Caillard from Flying Colours and what is their importance?

Colonel Caillard is responsible for accompanying Hornblower and Bush from Roses, Spain to Paris. He is a French official, who is described as cruel and paltry. Hornblowers sees him as quite similar in demeanor to Napoleon without the power to back himself up. Caillard is unlikable and seen as a symbol of France at its worst.