"You'll do no more murder at Hogwarts!"
-- Filius Flitwick
Alecto Carrow summons Voldemort before she is stunned by Harry. McGonagall and Amycus Carrow enter the Ravenclaw Common Room. When Amycus insults McGonagall and spits in her face, Harry attacks him. He tells McGonagall that Voldemort is on his way and Harry is working on Dumbledore’s orders to find something in the castle. McGonagall ties up the Carrow, declares that she prepared to fight to keep Voldemort out. As McGonagall with Harry and Luna (under the invisibility cloak) go to alert the Heads of Houses, they run into Snape. McGonagall duels him while Slughorn and Flitwick rush to her side and Snape flees. McGonagall and the other professors prepare the castle for battle as many alumni arrive to help defend Hogwarts from the Death Eaters.
Calendar and Dates
Immediately follows the preceding chapter, so still later on the same night in May.
Filch has been at Hogwarts for "a quarter of a century".
Interesting facts and notes
Slowly, they shuffled in around her, a savage beast that might wake at any moment and attack them. Then one brave little first-year darted up to her and prodded her backside with his big toe.
To me, this is a scene straight out of Roald Dahl (the film adaptation of Matilda for choice). I like it very much.
'Where do vanished objects go?'
Since Vanishing Spells are part of the fifth year Transfiguration curriculum, it's not surprising that McGonagall could answer this easily.
We must alert the other Heads of House.
The Heads of Hufflepuff (Pomona Sprout), Ravenclaw (Filius Flitwick), and Slytherin (Horace Slughorn), in other words. Slughorn was reinstated as Head of Slytherin House at the end of the previous year.
From the tip burst three silver cats with spectacle markings around their eyes.
McGonagall is using what we call the messenger spell - using her Patronus to communicate. Notice that it is the same as her Animagus form.
A good idea, since Peeves can make himself immensely inconvenient to any opponent and probably cannot be got rid of - and a distraction for the opposition during a duel is quite a weapon in itself.
Haven't you been complaining about him for a quarter of a century?
So Filch has worked at Hogwarts for about 25 years. We know he can't have been a student there, since he's a Squib (CS9).
a tiny baby with a tuft of bright turquoise hair
A Metamorphmagus like his mother, then.
Exceptional character moments
Sprout, without fanfare, saying that the defenders could at least delay Voldemort even if they couldn't stop him.
Filch, complaining about students being out of bed in the preliminaries of a shooting war.
Aberforth, having permitted Percy to make contact with him and trusting him enough to tip him off.
Percy, choosing sides before it's too late.
Molly, trying to protect the only one of her children whom she has a chance of ordering out of harm's way.
Ginny, trying to sneak off to the battle while everyone is distracted by Percy.
Fleur trying to distract everyone by asking Lupin about Teddy.
"'Couple of kids more or less, what's the difference?'
'Only the difference between truth and lies, courage and cowardice,' said Professor McGonagall, who had turned pale, 'a difference, in short, which you and your sister seem unable to appreciate.'"
"'I see what Bellatrix meant,' said Harry, the blood thundering through his brain, 'you need to really mean it.'"
"We teachers are rather good at magic, you know."
"A little extra wisdom never goes amiss, Potter, but I hardly think it would be much use in this situation!"
"Now let's get upstairs and fight, or all the good Death Eaters will be taken."