The movie establishes that the demons and goddesses had always been fighting each other, because the SD and the DK saw it as a way to maintain balance in the world. Apparently this was something they were born to do, which is presumably related to why Chaos created them. The SD refers to this as the Holy War, which could be seen as a retcon. It's also debatable whether their desire to keep the conflict going in perpetuity contradicts the fact that the goddesses eventually got desperate and triggered the COED, especially since that involved Gowther manipulating things to put an end to the war.
Alright, that's inline with what the manga set up towards the end, with the Demon King pushing the conflict while his sons didn't care for it. And I would assume that it came down to preferring the balance to be broken with them being victorious, as oppose to the balance being broken with the demon's victorious. Plus from what we were shown, even with the balance broken, Chaos wasn't necessarily capable of coming back without outside aid.
While it's true that the goddesses can manipulate people with their magic, we have seen this in action through characters like the Pleiades, as well as Dahlia and Dubs in the movie. It's easy to tell when someone is under the effect of mind control because their behavior becomes very erratic and overzealous. We also saw through Deathpierce that the effect wears off either after a while or when the caster is unable to keep it going. Realizing what had been done to him made Deathpierce despise the goddesses, so the other clans' attitude towards them would probably be similarly negative if they had all been unwillingly dragged into the war. The handful of sympathetic demons aside, it's not hard to see why the rest would be hated by the other clans.
It's not just magic though. We can see that in Ludociel's bargain with Margaret, and the way he treated her body. And as far as we know, they were dragged into the war. Afterall, we know how the first Holy War began, Meliodas switching sides. Gowther told us the goddesses then used that to seize the advantage. Original Gowther is the closest thing we have to an unbiased source, since he was opposed to both sides, and it fits with the flashbacks we were given. I wouldn't even say they were hated by the other clans, at least in the case of the giants. We know why Drole fought, and it was basically as proof of strength. It's not that there were sympathetic demons, it's that we were shown their reasons for doing what they did - the goddesses weren't just attacking demons, they were specifically targeting civilizes, which was shown out of line by the fact Ludociel hid it. Same appeared to be the case with original Gowther's lover. And the betrayal of the humans were due to Sigma casually wiping out an entire village, though it's not clear (at least in the manga) how many humans were apart of Sigma... We only see Rou's group of four, but it seems really crazy that four humans could have taken out dozens of giants, fairies, and goddesses.
The people captured were mainly those whom had fallen under Piety's mind control, which is why Merlin had to trick Zeldris into deactivating the curse. It's hard to say how the number of people captured would compare to that of the people living in hiding, especially when factoring in that the number of people on the surface also included people from Liones that fell under Piety during the demons' attack on Liones. This is further complicated by the fact that Nakaba never drew a wide shot accurately showing the number of people. The panels he did draw showed a few dozen people on the surface, a couple dozen underground and about a dozen that Nanashi had tried to save either successfully or unsuccessfully. It's also worth noting that the number of captured people was constantly decreasing during the occupation of Camelot. In chapter 234 Orlondi says "the demons are preying on all the brainwashed humans and sacrificing them in order to break the goddess' seal." The demons occupied Camelot for over a month, so who knows how many people were killed before the Sins even got there. And yeah, it makes sense that Arthur would be cautious of Meliodas and I also think there could be some truth to Chaos being largely a power of creation rather than that of destruction.
True, though that should have been everyone but the bravest. And yeah, it is hard to say, but based on the epilogue the combined number of people underground couldn't have been more then 30, and Nanashi seem to have saved more then died. That an unknown number were sacrificed is a major counterpoint, though those deaths would have taken place long before the destruction of Camelot.
It was never elaborated on so it's hard to say what exactly happened. All we know is that the alliance between Liones and the goddesses was formed at night and that by the time the battle started the next day, the giants and fairies had not only managed to gather their forces but also travel to the battlefield somewhere between Liones and Camelot, a distance of at least 100 miles from both Megadozer and the Fairy King's Forest. As for Talisker, you could take it that way, but to me "raze the earth" sounds more like Talisker just wanted Ordo to destroy the Gorge to prevent the fairies and giants from ever inhabiting it again. This kind of a less violent approach is consistent with his initial attempt to simply get Ordo to stop associating with them. Arthur desiring a land in which the other races don't exist to threaten humanity doesn't conflict with this approach either, because we know that the demons, goddesses and fairies have their own separate realms to live in, and that the giants are buddies with the fairies and could presumably live alongside them in the Fairy Realm. The demons are to be slaughtered, but the fairies and giants can just be forcefully evicted from Britannia. It's worth noting how similar this is to Deathpierce's view on things. He also wanted to build a kingdom exclusively for humans, but most of his hate was directed at the demons and goddesses.
Well as mentioned, the only reason I think the razing was meant more then that was because Ordo's actions did cause the majority to flee from the gorge, yet Talisker thought that was lenient and was still upset. Not much reason to be upset if he got what he wanted. And perhaps. But the way his knights speak appear a lot more fervent then merely wanting the other races to go their own way.
It's a bit of a stretch to say that the people of Sistana believed Ironside when we only saw a couple of lines of dialogue from them, including one saying "horrid, if it's true" which clearly displays skepticism. It also shouldn't be that difficult to convince people that Camelot was wiped out with only a few survivors when anyone can go visit the giant graveyard where the kingdom used to be. That's pretty strong evidence in support of the claim, especially when every adult in Britannia lived through the Holy War and should have at least a rough idea of what happened back then. As for Camelot's population, it's entirely feasible that almost all of them were killed during the events of NNT. Galand's attack alone leveled about a tenth of the kingdom, then you had the demons conquering it and using the souls of the mind controlled citizens to fuel the opening of the COED(potentially for over a month), and then lastly the DK showed up to vaporize almost everyone who was left behind. I mentioned earlier that Nakaba doesn't really draw scenes with large crowds so it's difficult to judge the numbers accurately, but we only saw the Sins rescuing a few dozen people, which included citizens of Liones, and then Nanashi rescued about a dozen more. For comparison, the graveyard shown in the movie was massive, with at least thousands if not tens of thousands of graves. I'd say Arthur's conflict with Liones is largely because Meliodas is the king in charge of its forces. It was shown in the final chapter that Meliodas is very popular among his subjects, so even sealing him away wouldn't make the kingdom stand down. Destroying them is the only way.
Fair enough, but one would think if something unbelievable was said, there would have been more outcry about it. Or they wouldn't have doubted Anne's words. Would that be easy? For the majority of people, traveling across the country wouldn't be an easy task in general, much less with the sort of dangers we know exist. True, but the majority of people would only know what happen to Camelot by being told, and what they're told wouldn't necessary be what actually happen. We saw this with the whole Danafor situation, which the believed truth was Meliodas destroyed it... The base for saving the most survived was Merlin's statement of that, and there isn't much reason to believe she was lying, as oppose to Cath attempting to trick Arthur. Without Meliodas though, Liones should hardly be a threat, no matter how loyal they are.
Donny was only ever a trainee knight and one who ran away some time ago to boot. Howzer not telling him about the details of the conflict, let alone any secret missions, isn't really on the same level as him not correcting Donny's basic misconceptions about recent historical events. Likewise with the COED, the only people who would know anything about that are those who were involved with the original Holy War or the conflict between the Sins and Liones back when Fraudrin was trying to obtain the pieces. Everyone pretty much forgot about the COED after the Ten Commandments had been freed, which in hindsight proved to be a really stupid move that almost resulted in Sistana getting wiped out and Meliodas being sealed away. Still, if even the Sins didn't care about the COED after it had served its purpose, it's not too surprising that normal people wouldn't even know about it.
Everything points to this conflict between them going on for the last 16 years, so Donny should've know that, especially since it would have been the reason for training in the first place. And it's more like the actual history isn't taught in Liones - we saw this with Tristan and how he had no knowledge of the truth about the Sins til specifically told. So unless Howzer went out of his way to discuss things, he probably wouldn't know what Donny knew or didn't know. That's presuming that Donny didn't merely learn this after running away.
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