Dumbledore's Army

Dumbledore's Army, or the D.A., was a secret organization started by Harry Potter, Hermione Granger, and Ron Weasley to teach students proper Defence Against the Dark Arts. This organization was made necessary by the refusal of Dolores Umbridge, the Defence Against the Dark Arts teacher in Harry's fifth year (1995-1996), to teach anything in her classes other than theory. There were 28 members for most of the meetings but Seamus Finnigan went to the last meeting and never signed the list.

History
D.A. meetings were stopped when Marietta Edgecombe, a member of the organization and daughter of Madam Edgecombe of the Floo Network Authority, tipped off Professor Umbridge about the meetings, thus becoming a traitor. Umbridge and her Inquisitorial Squad hurried to the Room of Requirement, where the meetings were being held. Most of the D.A. members managed to flee the room, but Harry Potter was caught and interrogated by Umbridge and the Squad. As their meeting room was no longer secret and Dumbledore's subsequent departure made the risk a severe punishment under Umbridge too great, the D.A. was not reassembled that year.

In 1996, the D.A. had appeared to disband due to there no longer being a need for the organization, as Dolores Umbridge had been replaced by Severus Snape as the Defence Against the Dark Arts teacher. Some members of the D.A. also participated in the Battle at the Department of Mysteries and the Battle of Hogwarts during the Second War.

Some of the members of the D.A. wanted to have more meetings so they could learn more DADA of higher levels that they were not learning in their current DADA class. However, Harry Potter thought that since Umbridge was gone that they did not need to meet any more, as he thought their purpose was to resist her.

Dumbledore's Army was revived during the 1997-1998 school year by Neville Longbottom, Ginny Weasley and Luna Lovegood due to the takeover of Hogwarts by the Death Eaters under the Headmastership of Severus Snape. This new generation of leaders, with the assistance of many former D.A. members, committed numerous acts of rebellion against Snape's leadership, including an attempted theft of Godric Gryffindor's sword from the Headmaster's office. Near the end of that fateful school year, several D.A. members, both current and alumni, aided in the final battle against Voldemort waged on Hogwart's grounds in which two members, Fred Weasley and Colin Creevey, died.

Appearances

 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows