In the fifth book, "Harry Potter and the Order of the Phoenix", the Ministry of Magic has been waging a smear campaign against Harry and Dumbledore, disputing their claims that Voldemort has returned. A new character is introduced when the Ministry of Magic appoints Dolores Umbridge as the latest Hogwarts' Defence Against the Dark Arts instructor (and Ministry spy). Because the paranoid Ministry thinks that Dumbledore is building a wizard army to overthrow them, Umbridge decides not to teach students real defensive magic. She gradually gains more power, eventually seizing control of the school. As a result, Harry's growing angry and erratic behaviour nearly estranges him from Ron and Hermione. Rowling says she put Harry through extreme emotional stress to show his emotional vulnerability and humanity–a contrast to his nemesis, Voldemort. "[Harry is] a very "human" hero, and this is, obviously, a contrast, between him, as a very human hero, and Voldemort, who has deliberately "de"humanised himself. And Harry, therefore, did have to reach a point where he did almost break down, and say he "didn’t" want to play anymore, he "didn’t" want to be the hero anymore – and he’d lost too much. And he didn’t want to lose anything else. So that – "Phoenix" was the point at which I decided he would have his breakdown." At Hermione's urging, Harry secretly teaches his classmates real defensive magic to thwart Umbridge and the Ministry, but their meetings are found and Dumbledore is ousted as Headmaster. Harry suffers another emotional blow, when his godfather, Sirius Black is killed during a battle with Death Eaters at the Department of Mysteries, but Harry ultimately defeats Voldemort's plan to steal an important prophecy and helps uncover Umbridge's sinister motives. Rowling stated: "And now he [Harry] will rise from the ashes strengthened." A sideplot of "Order of the Phoenix" involves Harry's romance with Cho Chang, but the relationship quickly unravels. Says Rowling: "They were never going to be happy, it was better that it ended early!"