Defence Against the Dark Arts

Defence Against the Dark Arts, also known as D.A.D.A., is a class taught at Hogwarts School of Witchcraft and Wizardry that focuses on defensive techniques to block spells, charms, curses, hexes, and jinxes cast by other wizards and witches, counteract the Dark Arts, and to protect from dark magical beasts and creatures such as the Boggart. Defence Against the Dark Arts is taught to Hogwarts students from the first year to the fifth, with the option of N.E.W.T. classes in the sixth and Seventh years for students who qualify.

Tom Riddle twice applied for the Defence Against the Dark Arts position, the first time shortly after graduation from Hogwarts. He was refused both times. According to Albus Dumbledore, after the second refusal, no Defence Against the Dark Arts teacher held the post for more than one school year. Dumbledore believed that this was due to Voldemort placing a curse on the position.

When Severus Snape first came to Hogwarts as a teacher, he applied to teach Defence Against the Dark Arts. Dumbledore refused, and instead offered Snape the position as Potions master, which he accepted. As D.A.D.A. teachers left the school, Snape regularly reapplied for the position, and was denied each time, in what Snape assumed was Dumbledore's fear of his relapsing as a Death Eater.

As D.A.D.A. teachers came and went at Hogwarts, it produced inconsistent learning from year to year, as the quality and style of teaching varied widely from teacher to teacher.

By the time Harry Potter came to Hogwarts, belief in a jinx had taken hold on the outside, and new teachers became difficult to recruit for the position. Gilderoy Lockhart was said to be the only applicant to replace Quirinus Quirrell. Three years later, belief in the jinx was so widespread that Dumbledore was unable to find a new teacher, and the Ministry of Magic appointed Dolores Umbridge to the job. After Umbridge was removed for her abusive nature, Dumbledore finally gave Snape the position.

Most of the D.A.D.A. teachers in Harry's first six years at Hogwarts followed a similar pattern: each (with the exception of Quirrell and Snape) was an entirely new teacher, each was chosen out of necessity, due to the loss of the previous instructor and the absence of other applicants, each meets Harry before he arrives at Hogwarts in the respective year (with the exception of Mad-Eye Moody who was only mentioned in passing), and each physically (or magically) attacks Harry during school term, either intentionally, or accidentally as in the case of Remus Lupin. Also, when Harry has a romantic relationship with someone, the D.A.D.A. teacher indirectly causes it to end: in Harry's fifth year when he becomes attracted to Cho Chang, Umbridge is given information from Cho's best friend Marietta Edgecombe, who uses it to come down hard on Harry. As a result, Harry and Cho got into an argument over Marietta, and fall apart. In Harry's sixth year, when he starts dating Ginny Weasley, Snape's murder of Dumbledore makes Harry fear that Ginny may be harmed if they keep seeing each other, so he ends the relationship.

Defence Against the Dark Arts professors
"You see, we have not been able to keep a Defence Against the Dark Arts professor for more than a year since I refused the post to Lord Voldemort."

- Albus Dumbledore

Galatea Merrythought
"Defence Against the Dark Arts. It was being taught at the time by an old Professor by the name of Galatea Merrythought, who had been at Hogwarts for nearly fifty years."

- Albus Dumbledore.

Professor Galatea Merrythought was employed over a hundred years ago, possibly by Headmaster Scamander, and was given an office on the sixth floor, which she owned for fifty years. It is likely that she taught Albus Dumbledore and Elphias Doge. During Tom Riddle's sixth year, Galatea decided to retire and left the year after. Riddle attempted to take her place, but Headmaster Dippet refused him the position.

Quirinus Quirrell
Quirrell was the Muggle Studies teacher at Hogwarts. After some time in the position, he travelled throughout Europe for a full term. After his return to the school, he was appointed as D.A.D.A. teacher, receiving little respect from students for his stuttering and jittery behaviour, supposedly from encountering vampires somewhere in Romania. He taught First years about the Curse of the Bogies, the Knockback Jinx, and the Lumos Charm, while he taught Fifth years about Vampire bats and Iguanas. Quirrell was killed at the end of the year after attacking Harry, sustaining excruciating pain while supporting the fragmented soul of Lord Voldemort in his own body.

Gilderoy Lockhart
Lockhart's tenure ended when he attempted to attack Harry Potter and Ron Weasley outside the Chamber of Secrets and was hit by a backfiring Memory Charm from Ron's malfunctioning wand. Lockhart was admitted to St Mungo's Hospital for Magical Maladies and Injuries with amnesia. Lockhart was presumably hired due to his reputation as an author, or perhaps because no one else wanted the job. Despite his inflated reputation due to having published respected books on Defence Against the Dark Arts, Lockhart was a fraud, and failed to fool the students of Hogwarts for long. By year's end, Lockhart was regarded by the students and teachers largely as a joke, and the majority of the school was elated to see him go. He taught his second year students about the creatures he supposedly defeated.

Remus Lupin
Lupin resigned after being revealed as a werewolf by Severus Snape, out of fears that the student's parents would not accept a werewolf as a Hogwarts teacher. Nevertheless, Lupin was enormously popular with the students and teachers, widely regarded as an effective, competent, and fair instructor and perhaps the best Defence Against the Dark Arts professor, particularly during Harry's school years; Hermione Granger even commented in fifth year that Lupin's exam was the only occasion where she and Harry both took a Defence exam from a teacher who knew what he were doing (Exams were cancelled in second year, and Harry was exempt due to his status as a Triwizard Champion in fourth year). Severus Snape stood in for Lupin as D.A.D.A. instructor for one of his third year classes when it was full moon. Many fans have assumed that Snape did so monthly during the school year, but this is unlikely, as he would have had his own classes and there would have been timetable clashes depending on which day of the week was full moon. It is more likely that other teachers such as McGonagall and Flitwick also filled in, but only Snape was ever explicitly stated to have filled in for one class. Lupin taught the third years about various Dark Creatures. Possibly Lupin's most significant piece of instruction was in teaching Harry Potter the Patronus charm.

Alastor Moody, impersonated by Barty Crouch Jr.
Moody, a retired Auror with the Ministry of Magic, was brought out of retirement to replace Lupin at Hogwarts and keep a protective eye on Harry Potter. As an Auror, Moody possessed many special magical devices, including a Sneakoscope, Secrecy Sensor, Foe-Glass, and other Dark detectors. He later turned out to be an impostor; Barty Crouch Jr. in disguise; having abducted the real Alastor Moody shortly before the school term began, using Polyjuice Potion to take on Moody's appearance. Crouch (as Moody) was nonetheless a very effective instructor, teaching the students true defensive skills and actively demonstrating the power of the Dark Arts, although an in-class presentation of the three Unforgivable Curses early in the year was controversial. After the discovery of Crouch's secret, Moody was released from captivity and returned to retirement; while Barty Crouch Jr, as an escaped prisoner from Azkaban, received the Dementor's Kiss. An interesting thing to note about Moody's period as teacher was that he briefly mentioned that he was only hired for the year anyway; whether this was truly the case or whether Crouch was lying at the time is left ambiguous.

Dolores Umbridge
Umbridge was assigned to the position acting as an agent for the Ministry of Magic and was later named Hogwarts High Inquisitor as the Ministry worked to gain control of the school. As D.A.D.A. instructor, Umbridge taught only theoretical aspects of defence and topics like conflict avoidance and fleeing, in stark contrast to practical combat and resistance teachings of the previous two D.A.D.A. instructors, and merely by making the students read from their textbooks, rather than teaching them herself. During Umbridge's tenure, Harry, along with Ron and Hermione Granger, provided clandestine D.A.D.A. instruction for their fellow students, based in part on some of the experiences Harry gained in his conflicts with Voldemort and others. They formed Dumbledore's Army, a secret club dedicated to training interested students in the practical elements of wizarding combat that Umbridge refused to teach. Umbridge was known to impose harsh punishments on Harry during her term, such as writing lines in his own blood during detention, as a way of forcing Harry to renounce his belief that Voldemort had returned to power. She challenged Dumbledore for his position as Headmaster, due to his support for Harry. Umbridge was removed from Hogwarts after Voldemort and his Death Eaters attacked Harry and his friends at the Ministry of Magic, which proved that he had returned to power and also proved the need for practical D.A.D.A. instruction for Hogwarts students. Umbridge was removed from Hogwarts immediately after the return of Lord Voldemort was announced by the Ministry.

Severus Snape
Snape assumed the post of D.A.D.A. instructor, unexpectedly by most of the students, and was replaced as Potions master by Horace Slughorn. Little is said about Snape's tenure as D.A.D.A instructor other than that he seemed to focus on non-verbal spells, defence against creatures and spells used by Lord Voldemort and his Death Eaters, and was looking after Draco Malfoy, who was acting enigmatically, for much of the term. He and Malfoy fled the school after the Battle of the Astronomy Tower, during which Snape killed Albus Dumbledore. The next year when Voldemort took over the Ministry, Snape was appointed headmaster of the school.

Amycus Carrow
In September of 1997, Carrow became the Defence Against the Dark Arts Professor at Hogwarts, although for that school year it was simply a class teaching the Dark Arts. Students were made to practise the Cruciatus Curse on other students who had received detention. Carrow was presumably arrested after Voldemort fell, and it is unclear who took over after him, although it has been mentioned that Harry Potter did sometimes come to teach D.A.D.A. as a guest teacher in the years following the Battle of Hogwarts.

Known O.W.L.s

 * Hannah Abbott
 * Susan Bones
 * Terry Boot
 * Lavender Brown
 * Michael Corner
 * Barty Crouch Jr.
 * Seamus Finnigan
 * Anthony Goldstein
 * Hermione Granger
 * Lee Jordan
 * Neville Longbottom
 * Ernie Macmillan
 * Draco Malfoy
 * Pansy Parkinson
 * Padma Patil
 * Parvati Patil
 * Harry Potter
 * Dean Thomas
 * Ron Weasley
 * Percy Weasley
 * Bill Weasley
 * Fred Weasley
 * George Weasley

Behind the scenes

 * When J. K. Rowling was asked for the reason Dumbledore would not give Severus Snape the Defence Against the Dark Arts job, the author responded that Dumbledore believed that teaching Defence Against the Dark Arts would bring out Snape's worst side, though Dumbledore finally relented in Harry's sixth year.
 * J.K. Rowling has also revealed that, after Amycus Carrow, a permanent teacher took the post, now that Voldemort's curse over the job was lifted.
 * Each Defence Against the Dark Arts teacher attacks (or attempts to attack) Harry. Quirrell tries to strangle Harry, Lockhart attempts to erase his memories, Lupin goes after him as a werewolf, Barty Crouch Jr. (disguised as Moody) attempts to kill Harry, Umbridge slaps him, tortures him and attempts to use the Cruciatus Curse on him, and Snape attacks Harry in retaliation for Harry trying to curse him during the Battle of the Astronomy Tower. Amycus Carrow, who taught the opposite of Defence Against the Dark Arts, was in turn attacked by Harry Potter after insulting Minerva McGonagall.
 * Dolores Umbridge is the only female Defence Against the Dark Arts teacher in the series, besides Galatea Merrythought.

Notes and references
Défense contre les Forces du Mal