Which organisation did this faculty of the wizarding school Hogwarts, with whom Harry prepares the final battle against Voldemort in his sixth year, found?
Harry Potter and the Half-Blood Prince:  Set during protagonist Harry Potter's sixth year at Hogwarts, the novel explores the past of Harry's nemesis, Lord Voldemort, and Harry's preparations for the final battle against Voldemort alongside his headmaster and mentor Albus Dumbledore. Albus Dumbledore:  As part of his backstory, it is revealed that he is the founder and leader of the Order of the Phoenix, an organisation dedicated to fighting Lord Voldemort.
i don't know