"Let us move forward, then, into a new era of openness, effectiveness and accountability, intent on preserving what ought to be preserved, perfecting what needs to be perfected, and pruning wherever we find practices that ought to be prohibited."
-- Dolores Umbridge, start-of-term feast speech (OP11)
The Ministry of Magic forces Headteacher Albus Dumbledore to appoint Dolores Umbridge to the staff for the 1995-96 school year (Harry’s fifth year). Due to Lord Voldemort’s “curse” on the Defence Against the Dark Arts teaching post at Hogwarts, there had not been any applicants for the position (OP11).
Umbridge is introduced to the students after the start-of-term feast, which we know from Harry's Hogwarts letter is 1 September. Since classes start the next morning, it must be a Sunday, although there is a discrepancy regarding the day of the week.
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Writing by J K Rowling on WizardingWorld (Pottermore): Dolores Umbridge
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