I thought “The Hundred Days” was probably the worst of the Aubrey/Maturin books. It was all based on the idea that there would be a mideast uprising in 1815 based on Bonaparte’s fake conversion to Islam in 1798. The muzzies weren’t fooled in 1798 and they certainly would not have believed it in 1815. Obviously, O’Brian had run out of plots by then.
You’ll get no argument from me on that. But it did have some merit. I admit that it’s been years since I read it, so your mileage may differ.