"Of the march of the host of Fionwe to the North little is said in any tale; for in his
armies went none of those
Elves who had dwelt and suffered in the Hither Lands, and who made the histories of those days that still are known; and tidings of these things they learned long afterward from their kinsfolk, the Light-
elves of Valinor. But at the last Fionwe came up out of the West, and the challenge of his trumpets filled the sky; and he summoned unto him all Elves and
Men from Hithlum unto
the East; and
Beleriand was ablaze with the glory of his arms, for the sons of the Gods were young and fair and terrible, and the
mountains rang beneath their feet."
Seems like JRR himself had said none of the Elves of Beleriand went there. But this is from a 1937 writing. In FOTR (1954)
Elrond clearly says he was present in the ruin of Thangorodim. Elrond! You know, a loremaster. Say what you want about him being still a
Half Elven who hadn't chose his
race until the end of WoW, but you can't deny that he became an
Elvish loremaster and he ought to tell
Bilbo and others about WoW. Elrond was there and naturally we should've known the details if he was there to witness and record these.
Moreover this is kinda vague. Is it saying that none of the Elves of Beleriand were with him during his march to the North but they came to him after he reached there and summoned them all?
Open for different interpretations I guess.
As for the question if the Elves of other side of the
Misty Mountains fought in WoW... No, they didn't. They didn't hear the summons of Eonwë. In one of
Galadriel versions where she passed to
Lorien in
First Age, it is explicitly said "too late she heard the summons of Fionwë"
