In 1984 what is the role of the Brotherhood, and why was it created?

The Brotherhood is the rebel group that is supposedly led by Emmanuel Goldstein. However, no one has ever seen Goldstein, and it’s hard to know whether the group even exists, given the fact that the Party makes up people and facts all the time in order to support its version of history. The group is supposed to be fighting to overthrow Big Brother, but in Chapter 8 of Book 2, O’Brien tells Julia and Winston that there is no feeling of solidarity in the rebel group; members can’t even recognize one another. It begins to seem odd that members of the Brotherhood are asked to do such violent things to people, and even the organization’s name is very close to the name Big Brother. As it becomes clear which side O’Brien is on, it seems that the Brotherhood is really a ruse created to smoke out traitors to the Party in Oceania. As far as readers know at the end of the book, the Brotherhood is simply a false claim made by the Party—and so merely part of the Party’s plan to squash the resistance.