In a book like Orwell's, you will find it difficult to break it down to 12 events. At the same time, there will be so many different voices clamoring for other events to be included as opposed to the ones that I include.  The more voices present, the better.  Yet, as with all issues of choice, it will be difficult and rather intense to reduce the intricate events of the novel into 12 events.

Event #1:  Winston writes the diary.  I think this would have to be one of the most important events in the novel because it sets into motion Winston's "awakening" and sense of resistance that makes him so fundamentally different than others in Oceania.  In contrast to Winston's job at the Ministry of Truth, one recognizes the rebellious act of writing in the diary because it seeks to reconfigure language as something subjective and personal.  At the same time, the mere act of writing the diary showcases the extent of centralized control in Oceania.  

Event #2:  Winston's First Experience with Two Minutes Hate.  The flashing of Goldstein's image on the screen during the Two Minutes Hate is a significant event because it shows how Big Brother deals with those who lie outside of established parameters.  It also illustrates the extent to which the government goes to to eliminate and target those who are "outsiders."

Event #3: The fleeting image of Winston's mother.  Winston has only a passing image of his mother.  It illustrates the extent to which emotional bonds are frowned upon, a condition of centralized totality in which Big Brother controls all, including the emotional quotient of its citizens.  

Event #4:  Winston meets Julia.  This is one of the most important events in the novel because it sets in motion everything afterwards.  Winston's affair with Julia is significant for a couple of reasons.  One of the most relevant is that the relationship goes against what the Party states is the only purpose for carnal interaction.  The production of children is the only reason why men and women interact.  Winston recognizes in Julia both danger and potential elation in their first interaction: "In front of him was an enemy who was trying to kill him; in front of him, also, was a human creature, in pain and perhaps with a broken bone.”  The dynamic of something being both beautiful and dangerous is an initial impression that underscores their entire relationship.  As Winston meets Julia and they both begin to engage in a relationship that acquires both emotional significance and political resistance, it becomes extremely important to the novel's development.

Event #5:  Winston and Julia walk into a field.  I think that this is an important event in the novel because it symbolizes a realm that Big Brother cannot permeate.  The walking together, arms intertwined, is one of the purest forms of expression that both can experience in a world where Big Brother wishes to control everything and everyone.  For one moment, Winston and Julia can exist in a world free of Big Brother watching them.

Event #6:  “It’s nothing, I don’t like rats, that’s all.”  This is a fairly important moment in the novel because of its foreshadowing effect.  Winston and Julia lie in bed together when Winston discloses to her how he has a fear of rats.  This very fear is going to be what will be used later on in in the narrative.  At the same time, the "rat" is going to infiltrate their world very soon, adding to the symbolic nature of the moment.

Event #7:  Winston takes O'Brien as an Accomplice.  This is an important moment because it is the beginning of the end.  Happening in Part 2, Chapter 6, Winston is beginning to show signs of strength against the Party.  He is becoming more confident in his resistance stance.  Yet, when he is gripped a small segment of his own past in the association with O'Brien:  "He had the sensation of stepping into the dampness of a grave, and it was not much better because he had always known that the grave was there and waiting for him.”  Despite this physical and emotional improvement, it is only a matter of time before Winston meets his end.

Event #8:  The Prole Woman Singing Outside the Window. When Winston notices the Prole woman singing, it is significant because it marks the apex of Winston's political understanding.  He understands that if the Proles were to unify and coalesce around a common goal of eliminating Big Brother, there is a very good chance of change happening.  The song and the moment are significant because they represent an instant before change is thrust upon he and his world.

Event #9:  Winston and Julia are busted.  Charrington is a member of the Thought Police, Winston's paperweight is destroyed, and their affair becomes knowledge that Big Brother appropriates in order to imprison them.  Nothing will be the same from this point on in the narrative.

Event #10:  “Who controls the past controls the future: who controls the present controls the past.”  Winston is imprisoned and his torturer is O'Brien. It becomes clear that the torturing that happens in Room 101 is designed to eliminate any last vestige of humanity in the individual.  It is also designed to assert the unquestioned power of Big Brother.  This is important because it shows the savagely brutal nature of Big Brother and the Party.

Event #11:  The betrayal.  Using Winston's fear of rats as a motivator to get him to betray Julia, Room 101 fulfills some of the worst in techniques of interrogation.  As he is desperate to save himself from his worst fear of rats, he betrays Julia.  This moment is important because it shows the lengths to which Big Brother goes to ensure complete control over its citizens.

Event #12:  "Snakes and Ladders."  The ending scene in the book is one where the wreckage of Winston's life is evident.  The recollection of how Winston and Julia run into each other, both confessing their betrayal of the other is a painful moment in the novel.  At the same time, the way in which they lose sight of one another reflects the terror within Oceania.  The last moment in which Winston vaguely recalls a happy time with his mother strikes a note of melancholy in a life that is destined to meet its end very soon.

In these events, one sees the range of the human predicament.  The hope of what can be as opposed to the reality of what is drives the selection of these events as significant in Orwell's work.