He’s talking about Zaheer and the Red Lotus. They were extremely well intentioned, but set about their goals with violence.
I’ll never stop complaining that in the second movie Dooku tells Obi-Wan that the Separatists are the good guys and that there’s a sith influencing the Senate. Which would have been a cool reveal for the audience, that we’re rooting for the bad guys.
But then Dooku is also a sith anyway. What a wasted opportunity.
A sad day for both England, and the world.