Is Thranduil actually Daeron?

[Mattius]

There was a wonderful little snippet in Unfinished Tales, tellling of Oropher's hasty, ill-equipped charge against the gates of Mordor, his death, and how the experience scarred Thranduil for his long life. It's on pages 258-259 of Unfinished Tales

I have Unfinished Tales but I must have a different edition to yourself. By any chance could you tell me the chapter it is in etc.

Thanks!

Matt