Rebels at the 3rd kinslaying

[Elemmírë]

If anyone reading or wanting to get involved doesn't have a copy of the Silm at hand, I'll put the passage in question here:

Now when first the tidings came to Maedhros that Elwing yet lived, and dwelt in possession of the Silmaril by the mouths of Sirion, he repenting of the deeds in Doriath withheld his hand. But in time the knowledge of their oath unfulfilled returned to torment him and his brothers, and gathering from their wandering hunting-paths they sent messages to the Havens of friendship and yet of stern demand. Then Elwing and the people of Sirion would not yield the jewel which Beren had won and Luthien had worn, and for which Dior the fair was slain; and least of all while Earendil their lord was on the sea, for it seemed to them that in the Silmaril lay the healing and their ships. And so there came to pass the last and cruellest of the slayings of Elf by Elf; and that was the third of the great wrongs achieved by the accursed oath.

I would personally interpret it the way that Artanis does.