Battle of the Astronomy Tower

The Battle of the Astronomy Tower, also known as the Battle of the Lightning-Struck Tower, was a battle of the Second Wizarding War that took place in the topmost tower of Hogwarts School of Witchcraft and Wizardry in June of 1997. It occurred per the design of Lord Voldemort, who had ordered sixteen-year-old Death Eater Draco Malfoy to find a way to sneak other Death Eaters into the school and to assassinate Albus Dumbledore, the leader of the Order of the Phoenix. Malfoy succeeded in the former, but was unable to do the latter. As the Order and the Death Eaters battled, Severus Snape killed Dumbledore, an act that was later discovered to have been planned between Dumbledore and Snape.

Background
As a result of Lucius Malfoy's failure at the Battle of the Department of Mysteries in June of 1996, Lord Voldemort decided that Lucius's son Draco should become a Death Eater, and that he should carry out the mission of killing Dumbledore. Narcissa Malfoy suspected that this was revenge from Voldemort and that the Dark Lord did not expect Draco to fulfil his mission. Determined to save her family, Narcissa ventured to Severus Snape's house at Spinner's End to ask him to help Draco and to complete the mission if the boy was unable to do so. Snape asked Bellatrix Lestrange, who had reluctantly accompanied her sister, to bind him and Narcissa with an Unbreakable Vow.

Draco spent most of his sixth year at Hogwarts repairing a Vanishing Cabinet in the Room of Requirement in order to connect it with the one at Borgin and Burkes so that Death Eaters could enter Hogwarts Castle. During periods of desperation, Draco invented more conventional ways to kill Dumbledore. He placed the Imperius Curse upon Madam Rosmerta, who in turn placed the Imperius Curse on Katie Bell to give a cursed necklace to Dumbledore; however, Katie accidentally touched the necklace and suffered from the curse instead. Draco also made Rosmerta sell Horace Slughorn a poisoned bottle of mead, anticipating he would give it to Dumbledore as a Christmas present, but Ron Weasley was accidentally poisoned instead, though Harry Potter was able to save him with a Bezoar.

Later in the school year, before leaving the castle with Dumbledore to seek one of Voldemort's Horcruxes, Harry met Sybill Trelawney who told him that she had been unable to enter the Room of Requirement, and had heard someone expressing his triumph. Nonetheless, Dumbledore and Harry left the school to look for the Horcrux.

Death Eaters enter Hogwarts
Harry had warned Ron, Hermione, and Ginny that, during his and Dumbledore's absence, Death Eaters might penetrate Hogwarts. Hence, he gave them Felix Felicis and told them to ask Dumbledore's Army members to help them patrol the corridor of the Room of Requirement, as well as Snape's office. Only Neville Longbottom and Luna Lovegood answered the call. While Ron, Ginny and Neville kept guard outside the Room, Hermione and Luna were stationed outside Snape's office. Dumbledore had also asked members of the Order of the Phoenix to patrol the corridors and the grounds.

Draco used Peruvian Instant Darkness Powder so that Ron, Ginny and Neville could not see the Death Eaters leaving the Room. The students immediately went to alert the Order, and the battle began in the corridors of the upper floors. In order to catch Dumbledore's attention, Death Eater Gibbon placed the Dark Mark above the castle, but after he returned to the battle, he was accidentally killed by fellow Death Eater Thorfinn Rowle, who was sending Killing Curses all over the place. Filius Flitwick was sent to ask Snape to join the battle. However, the Charms professor was knocked out by Snape, who then told Hermione and Luna that Flitwick passed out and asked them to look after him.

Dumbledore's Death
Dumbledore and an invisibility-cloaked Harry are confronted atop the tower by Draco Malfoy, and before Harry can reveal himself, Dumbledore immobilizes Harry with a silent spell. Malfoy disarms Dumbledore, who sacrificed the time to defend himself to immobilize Harry, and admits that he, Draco, was behind a series of attacks on Hogwarts students, and that Voldemort has ordered him to kill Dumbledore. Dumbledore offers Draco the chance to change sides, and promises to hide Draco and his mother where Voldemort will never find them. Draco cannot bring himself to kill the headmaster, when suddenly Snape - who has also seen the Dark Mark - arrives and casts the Killing Curse, killing Dumbledore.

After Dumbledore's corpse plummeted down the tower under the light of the Dark Mark, Snape dragged Draco by the collar and ordered the rest of the Death Eaters to immediately flee the tower, and went downstairs to order the fighters there to follow. Harry, who was forced to watch the entire spectacle from the Full Body-Bind Curse, was set free upon Dumbledore's death, and in an enraged desire for revenge, he immediately set off to pursue Snape, stunning Yaxley in order to get a clear way down the stairs.

Pursuit
Free from the Body-Bind Curse, Harry stunned Yaxley, who was the remaining Death Eater in the tower, and proceeded to pursue Snape. Just as he entered the castle, Harry found himself in full battle, as Order and D.A. members were still fighting the fleeing Death Eaters. Harry saw the dead body of Gibbon, as well as a severely wounded Bill Weasley on the floor; he had been brutally attacked by Greyback. As Harry got rid of the werewolf, he saw Ginny duelling Amycus, and Nymphadora Tonks trying to contain Rowle, who was still causing great damage. All of the Death Eaters, however, began to retreat on Snape's orders before the Ministry arrived to reinforce Hogwarts. Harry used Hogwarts' secret passages to try to reach Snape, who was already reaching the grounds.

In the grounds, Rubeus Hagrid tried to stop the fleeing Death Eaters, but his hut was set on fire. Harry himself was cursed as he was trying to attack Snape. Once Draco and the other Death Eaters had reached the gates and Disapparated, Harry confronted Snape and tried to used some of his spells against him, but Snape repelled all of them. After revealing that he was the Half-Blood Prince — the owner of the Potions textbook Harry had been using all year — Snape cast an unknown spell on Harry, but the boy was aided by Buckbeak, who chased Snape until he Disapparated at the school gates.

Aftermath
Because of their use of Felix Felicis, the members of Dumbledore's Army who fought in the battle were unharmed. Bill Weasley, however, was left horribly scarred by Fenrir Greyback's attack. Because the Werewolf was not transformed when he brutalized Bill, his victim only retained mild lycanthropic symptoms, such as a taste for very rare steaks. His fiancée Fleur Delacour reaffirmed her desire to marry him, earning the respect of her future in-laws and prompting Nymphadora Tonks to declare her love for Remus Lupin.

The battle and Albus Dumbledore's death had a great impact on the wizarding world. Hogwarts staff members were not even sure whether Hogwarts would remain open. Some parents, such as Zacharias Smith's father and the parents of Parvati and Padma Patil, arrived to get their children out of the castle. Others, such as Seamus Finnigan's mother, stayed in Hogsmeade and waited until after Dumbledore's funeral to collect their children.

Harry, devastated by his mentor's death, decided to forgo his last year at Hogwarts in order to search for Lord Voldemort's Horcruxes, per Dumbledore's instructions. Ron and Hermione committed themselves to helping him.

Harry would later discover that Dumbledore's death had been according to his own plan, as devised between him and Snape, who was loyal to the Order of the Phoenix out of lifelong love for Lily Evans, Harry's own mother. Dumbledore was already dying, and wanted Snape to give him a more merciful end than he would receive at the hands of Death Eaters and to avoid making Draco Malfoy into a murderer and damaging his soul. Snape fulfilled his wish, and although the Order thought him to be a traitor, Snape was covertly assisting Harry, and thus contributing to the defeat of Lord Voldemort.

Behind the scenes

 * According to David Heyman, the Battle of the Lightning-Struck Tower was left out of the sixth film because, as there is another battle at Hogwarts (the actual Battle of Hogwarts) in the eighth film, they are trying to avoid repetition.
 * Chapter 27 of Harry Potter and the Half-Blood Prince, in which most of the battle occurs, is titled "The Lightning-Struck Tower". Earlier in the novel, Professor Trelawney mentions having drawn the tarot card The Tower in a reading and how Headmaster Dumbledore was ignoring her warnings that this foreshadowed "calamity...coming near all the time". In Divination, this tarot card — usually depicted as a town being struck by lightning — is usually taken to mean catastrophe and chaos, much like the Battle of the Astronomy Tower. However, it can also mean epiphany and the letting go of pretences (illusions or self-delusions) one has clung to, which Harry was forced to do following Dumbledore's death.
 * When Harry Potter is running after Severus Snape he notices the Gryffindor Hourglass is broken and its rubies are being spilled across the floor. This could be a symbolization of Gryffindor losing its greatest member, where as in the Battle of Hogwarts the Slytherin hourglass is struck and emeralds are on the floor foreshadowing Lord Voldemort's death as Slytherin house's greatest member (or perhaps Snape's death).
 * David Yates has announced that the Battle of the Astronomy Tower will be in Part One of Harry Potter and the Deathly Hallows. *Evanna Lynch, Bonnie Wright and Matthew Lewis are all confirmed to be in the scene. Also, the four heads of houses, Maggie Smith, Jim Broadbent, Miriam Margolyes, and Warwick Davis are confirmed to be there.

Appearances

 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (video game)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part I