Tolkien Tide: Of the Coming of the Elves and the Captivity of Melkor
This is really the first time where it's evident at all that this book isn't finished. And even then, it's only evident because I've read Tolkien for so long; it hangs together perfectly well. But the two stories herein only barely go together, and it seems like something he would have figured out in another revision pass.
What I mean by that is we have the story of the Valar finally deciding enough is enough and that they need to go get Melkor's ass and throw him in god-jail.
(Hades 2 spoiler): Insert image of Hades in chains from Hades 2 here. And then we have the elves awakening and Orome discovering them, then leading them slowly towards the shore so they can sail to Valinor. These stories happen next to each other, but they aren't obviously connected. The connective tissue comes in the discussion the Valar have when they decide to finally do something about Melkor. Yavanna travels into Middle-Earth regularly, to check on her plants and animals. She realizes, better than most other Valar, how bad it's gotten because Melkor is unchallenged there, and tells the Valar they must deal with him before the elves awaken, lest they suffer. This argument works, and they eventually root him out.
There are two points of contact aside from that: the elves do awaken before Melkor is subdued, and see far off the great lights of the battles. Also, since Melkor knew the Valar would come, and Orome was likely to find them, as the other god who travels Middle-Earth, Melkor created shadows in the form of riders to try to frighten the elves so badly they would not trust Orome. It works on some, too -- they are the first, but not the only, splinter group of elves who refuse to follow Orome to the sea.
The rest of the story tells of how the elves slowly wander west, whenever Orome guides them. They have long fallow periods where he leaves and they just settle down. More and more elves depart, though here we don't get numbers. Given what I've read of Tolkien's work calculating population numbers and rates of aging, I'm certain he had some idea of how many elves began the journey and how many quit, but that doesn't appear here, as this is meant to be a chronicle, and an in-universe one at that (there is a narrator, with a light touch, but who does often point out that "the wise" are the source of this information, and that we don't know certain facts. One group of elves is described as "forgotten" because they quit the journey, for instance; given the importance of Legolas, we can safely assume Tolkien didn't think the "wild" elves unimportant, even if he was more interested in those who traveled to Valinor).
This is also the chapter that tells us the now-infamous fact that orcs are elves that Melkor took and tormented. Many (many) writers have dealt with the implications of that for the race and colonial politics of the books. What I want to say is that this creates a discomfort -- Tolkien knew, I think, what he was doing, even if yes he was absolutely influenced by his culture's colonialism (as one always must be one way or the other). We learn here that the orcs always hated, in their hearts, Melkor and, by extension Sauron. They don't want to be doing this, they can still feel they are serving their tormentor. But they have no other choice, and have been twisted until they do in fact enjoy violence and brutality for their own sakes.
Thaliarchus has written recently about the orcs and their attitudes, as has Executive Otaku.
A final note: probably unsurprisingly, but worth pointing out in passing, Orome discovers the elves not by seeing them but by hearing them (and in fact his mount hears them first). They are singing. As the firstborn of the Children of Iluvatar, they sing naturally. The implication, I think, is that humans too would naturally sing, if they gave up their distractions.