The church and the Vampires obviously had a truce for the last thousand years... Well the inquisition was doubtlessly the Church vs. the Vampires (unless witches, who are real and not made up, used to be a really awwwwwwwwwful problem?) so lets say they've had a truce for the last 400 years.
It was Benedict.
He takes over insisting that an answer to the Vampires be found, and now that they're all dead by their guestimates, he feels confidant enough to retire since he was a Battle-Pope and this is peace time which he has no stomach for.