In the last Olympian Percy’s says there were 40 demigods that went fighting into battle of manhattan and later on the ares cabin joined so they weren’t even counted in that 40.
And in the end of the book Percy’s says there were only about “20 odd” demigods that survived and made it back to camp.
Roughly half of the whole entire camp perished in battle of manhattan.
And I’ve done the math and figured out who all the veteran characters are. Most of these are all characters mentioned both before and after the battle of manhattan and some of them were introduced in HoO but said to have been at camp since the titan war. These are the only known true survivors of BoM and it adds up to about 20. This is all of them. None of them are unknown. Do with this what you will
All of the battle of manhattan veterans in order of their cabin numbers :
Can you imagine them all going back to camp together in only of those Delphi strawberry busses when they came in four busses. All of them together in a tiny bus grieving their lost siblings together.
Percy Annabeth And Nico went on a wild goose chase after Rachel who had just highjacked Black Jack and that’s how they got back to camp they weren’t on the bus.
Malcolm was all alone and might have believed Annabeth died out there in the streets somewhere or in the Empire State Building. (He’s elated to find her alive at camp later. But god that was a scary couple of hours on the bus thinking he’s all alone now)
Malcolm sits with Butch and Pollux because they’re the only other campers on the bus without siblings. Butch just because he happens to be the only known iris kid at camp and Pollux because he lost Castor in battle of the labyrinth.
All the others sit with their siblings. Or what’s left of them. Entire large cabins that used to have 10-20 kids on average now reduced down to 1-3 kids. Some died. Some joined Luke and probably died soon after.
Edit : And since I’ve seen some Titan army hate in these comments for no reason here’s something else I should have said.
If they joined Luke but somehow survived they were probably wrongfully murdered by the gods for rebelling or brutally punished somehow like Alabaster Torrington. So many titan army kids perished too. Don’t forget them. They fought for a noble cause. They didn’t die for nothing. They were just kids with dreams of making things less shitty for everyone. They suffered just as much if not more than the camp halfblood kids all at the hands of the gods and the titans and even other demigods that were higher up on the Olympus hierarchy. Nico, Ethan, any kid who’s not a child of the big 12 were not treated as equals at camp back then just because of their parentage or lack of powers or unique or scary powers. A lot of titan army kids were from minor gods who suffered because of the big 12 and their children. Camp halfblood wasn’t so nice to them in fact pretty cruel and rude and mean just because of that stupid hierarchy. Of course they felt hurt and fell into Kronos’s trap of trying to make things better. Of course Luke being their counselor at camp cause Hermes takes in all the minor god kids saw all them suffering and tried his best to help. Of course Luke fell into Krnos’s trap as well. and I refuse to tolerate any hate or misunderstanding of them.