OH whoops, missed a part.  Why lie?  Because Lord Varya consumes all, but in reality, a nation that is going to have the same fighters die in battle executed following a surrender, as well as their ruling family, is a LOT less likely to surrender.  Especially Lanostre, though they did have their goddess do that...might be some conflict internally because of that.

T'sarae surrendered before even fighting, and they were the first, so perhaps they didn't know what would follow.  Actually, I guess...given that the other two are one unclear and one fighting to the bitter end, it's conceivable that killing everyone in those groups is feasible.  It's just that people tend not to like that sort of thing.  Most people don't surrender when surrender means death, and other people tend to get angry about it (though that's in our world, where there's a standard of not killing those who surrender).  [@Lovejoy]