In 1984 how does Room 101 help O’Brien accomplish the Party’s mission?

The Party’s goal is to maintain its absolute power over people, and Room 101 breaks down even the most resistant of rebels by destroying their humanity and the dangerous emotions that threaten the Party’s mission. In the room dissidents are tortured by whatever they fear most. This is the moment at which the Party breaks people down completely and forces them to accept Party dogma. For Winston this nightmare involves rats—which doesn’t surprise the careful reader, because, earlier in the novel, Winston expresses fear of a rat in the room above the antique shop. Terrified beyond description at the prospect of having rats eat his face, Winston calls out, “Do it to Julia! Do it to Julia! Not me! Julia! I don’t care what you do to her.” When O’Brien hears this, he knows Winston has lost his humanity and will never defy the Party again.