Chapter 27 of Harry Potter and the Half-Blood Prince: The Lightning-Struck Tower
Harry Apparates a weakened Dumbledore back to Hogsmeade. Collapsing, Dumbledore tells Harry to get him to Severus Snape. Madam Rosmerta runs up, reporting that the Dark Mark is floating over Hogwarts. She lends them brooms, and they fly to the Astronomy Tower, with Dumbledore mumbling incantations to allow them through Hogwarts' protective spells. Harry fears for his friends' lives.
As they land atop the tower, Dumbledore orders Harry to fetch Snape, but hearing footsteps in the stairwell, petrifies Harry under his Invisibility Cloak. Draco Malfoy bursts through the door and Disarms Dumbledore. Draco reveals that his task is to murder Dumbledore, and that he has helped the Death Eaters invade Hogwarts via a Vanishing Cabinet that he repaired. Draco also used the Imperius curse on Madame Rosmerta, forcing her to poison the bottle of mead and to send the deadly necklace to the school.
Malfoy seems reluctant to kill Dumbledore, but believes he has no other choice, as his and his mother's lives are at forfeit should he fail. Dumbledore calmly reasons with the frightened and conscience-stricken boy to abandon his mission, promising protection from Voldemort. Malfoy falters, apparently considering Dumbledore's offer. As he lowers his wand, four Death Eaters arrive: Amycus and Alecto Carrow, Fenrir Greyback, and one other. Despite their taunts spurring on Draco, he is unable to kill Dumbledore. Harry, still immobilized under his Cloak, can hear the Hogwarts defenders yelling below as Snape suddenly appears on the scene. When Dumbledore calls out his name almost pleadingly, Snape, revulsion and horror on his face, casts the Killing curse directly at him, hurling Dumbledore's lifeless body over the parapet and to the ground below, Harry watching in frozen, silent terror.
Perhaps the greatest mystery in the entire series is, did Snape actually murder Dumbledore or was there a prearranged plan? Evidence supports either conclusion, and despite Dumbledore's unwavering trust in Snape, his loyalty remains questionable to Harry and readers. Regardless, it appears that Snape had little choice; he must either kill Albus Dumbledore or die, since he is bound by the Unbreakable Vow to protect Draco Malfoy and complete his mission should Draco fail. Though many readers may believe that if Snape was truly loyal to Dumbledore, then he should have willingly sacrificed himself to protect him and Harry, yet he does not. It is possible that Snape and Dumbledore were communicating with each other using Legilimency, and Dumbledore's pleas may represent a request for Snape to sacrifice him to protect Harry and allow Snape to remain in the Dark Lord's favor, implying that Snape might play a key role if Harry is to destroy the Dark Lord. These speculations, and whether or not Dumbledore was actually dead, were hotly debated by readers until the seventh and final Harry Potter book was released.
Whenever the Avada Kedavra curse has previously been seen, the victim merely collapsed and died. Yet in this instance, Dumbledore is hurled into the air and spun around before falling dead to the ground. This was cited as evidence that Snape's curse was not actually the killing curse, but something else; it was suggested that he had spoken the Avada Kedavra incantation, but had actually voicelessly cast something like Expelliarmus, to make it appear that Dumbledore was dead but sparing his life.
Snape's killing Dumbledore may not actually be murder. That is, there may have been a prearranged agreement that Snape would kill the Headmaster if events deemed it necessary to protect the Order's and Harry's missions. Indeed, during their confrontation on the Astronomy Tower, Dumbledore is almost pleading with a conflicted Snape to curse him. In a previous conversation between them, Snape was overheard telling Dumbledore that he would refuse to do something, to which Dumbledore insisted he must follow through. This may have been a reference to Snape's Unbreakable Vow that would require him to kill Dumbledore if Draco failed.
Voldemort himself may have unintentionally prevented Dumbledore's death. When Dumbledore drinks the potion in the cave, he says it will not immediately kill him, because Voldemort would want to keep whoever stole the locket alive long enough to learn how he was able to penetrate the Dark Lord's defenses. Is it possible that the potion protected Dumbledore from the Avada Kedavra curse, keeping him in a deathlike state? If this were true, there may be an antidote to the potion's poisonous effects, and which could be why Dumbledore wanted Harry to fetch Snape rather than Madam Pomfrey, when they returned to Hogwarts.
Countering these speculations is the author's assertion in an interview after the sixth book's release that Dumbledore is "definitely dead." And though Rowling has often planted "red herrings" in the storyline, she has never been prone to outright deception by issuing false statements to her fans. The Headmasters do live on, in a fashion, within their portraits, interacting with people and retaining the headmasters' memories. Should Dumbledore's portrait appear in the Headmaster's office, to join the other portraits there, it should be able to speak with Harry and provide information regarding unresolved events. Additionally, Dumbledore will also have stored memories in his Pensieve, which Harry may be able to access.
In previous books, Rowling included a particular character who demonstrated suspicious behavior (e.g. the implication that Snape was trying to steal the Philosopher's Stone in book 1), before revealing it was actually someone else (e.g. Quirrell was attempting to obtain the Philosopher's Stone). Given her tendency to plant red herrings, it is impossible to say conclusively where Snape's loyalty lies. His actions have been such that he has been useful to both sides, and he has done nothing that would force him to choose one over the other.
Dumbledore seems either to have been intending to die or was taking a tremendous gamble. The Death Eaters were able to quickly conjure an impenetrable barrier on the stairway, which begs the question why Dumbledore did not react similarly after hearing footsteps on the Astronomy Tower staircase. This would have allowed both Harry and himself an opportunity to escape, but instead he chose to incapacitate Harry, preventing him from intervening and allowing himself to be disarmed by Draco Malfoy, an unqualified wizard. He was either expecting (or planning) to be killed by either Draco or Snape, or he hoped to turn Malfoy over to his side. Dumbledore's already seemingly weakened condition, followed by the events in the sea cave, may have left him extremely vulnerable, resulting in his failure to defend himself and Harry against this attack.
- If Dumbledore did not know about Snape's Unbreakable Vow, he nevertheless suggests to Draco Malfoy that "perhaps Severus may have told you so," implying that Snape might not really be disobeying Dumbledore. Is it possible he was bluffing to Malfoy?
- Why did Malfoy choose Madam Rosmerta to be his spy? Explain in detail.
- Why did Dumbledore paralyze Harry Potter under his Invisibility Cloak upon Draco's arrival on the Tower?
- Why would Snape kill Albus Dumbledore? Was it ruthless murder or a prearranged plan?
- If Snape actually is loyal to Dumbledore (as Dumbledore always claimed), why wouldn't he be willing to sacrifice himself to save Dumbledore and Harry?
- Why did the Avada Kedavra curse affect Dumbledore differently than it has others?
Nothing is mentioned in this chapter about what happened to Dumbledore's wand after Draco sent it over the tower parapet. However, it is revealed in book seven that the wand was interred with Dumbledore's corpse, and it becomes an important plot element in the final showdown between Harry and Voldemort.
Dumbledore's death was, we discover later, premeditated by both himself and Snape; Snape was charged to kill him at an appropriate time to spare Malfoy from completing Voldemort's task, thus saving Draco's soul, which would be forever damaged by committing murder. Dumbledore was slowly dying from a deadly curse that was inflicted when he put on the now-destroyed Horcrux (Gaunt's ring). Wishing to die by his own design, to spare Draco's soul, and to retain the dignity that Death Eaters such as Fenrir Greyback or Bellatrix Lestrange would have denied him, Dumbledore tasked Snape with his death. The potion Dumbledore drank in the cave had left him too weak to defend himself. His final plea to Snape was not to spare him, as Harry naturally believed, but to carry out his final wish, which Snape reluctantly executed.
It is never explained why Dumbledore allows a Cloaked Harry to witness his death. We can only guess at his motives, though the circumstances may have prevented him from making another choice. Dumbledore, who has known that his death is impending, fully expects that either Draco or a Death Eater is on their way up the tower. Dumbledore has stated that Harry is far more valuable than he is himself, and so his primary purpose is to protect Harry and keep him out of the battle. Dumbledore knows Harry will defend him and would be over matched by the invading Death Eaters, so he disables Harry. Whether Dumbledore deliberately chose the freeze spell that would immediately free Harry upon Dumbledore's death, must remain unknown. The nature of the spell, Harry's witnessing the events atop the tower, and his immediately being released from the spell's effects, is clearly necessary from the author's viewpoint. Our protagonist must see these events at the book's climax.
As a side note, the unnamed fourth Death Eater present at Dumbledore's death, is later identified as Yaxley. Yaxley, a Death Eater in Voldemort's old organization, will play a moderately significant role in Harry Potter and the Deathly Hallows.