He sighs. The Dementors are only half of the problem regardless. When he does destroy them he will still need a replacement system ready to go and there’s simply no one to contract domestically. Gringotts is very efficient at sweeping up any nascent Curse-Breakers or Warding Masters in Britain -- what few the country produces, given the lack of offering necessary courses in Hogwarts for the last 50 years. The French have a prison system worth emulating and the warding experts necessary to create or adapt a current scheme, and are utterly unwilling to work with him under fear that he will invade them.