What is the biggest lie you ever told? What were the consequences?
I'd known the whole thing was somehow wrong, right from the start, though I couldn't quite explain how. We were standing up against the ultimate evil, right? Morgoth had taken what did not belong to him, had threatened the very stability of Arda, and needed to be stopped.
And yet blood was shed from the very beginning, when we stole the ships from the Teleri, and then burned them so that Nolofinwe's host could not follow. I had refused any part in the burning of the ships, for I believed that it would keep Findekano from me for ever. After there was nothing left but charred remains, my father approached me and took me aside.
"I do not expect any further defiance from my eldest son," he said to me coldly. "Either you are on my side, or you are on his," (meaning Morgoth).
Shortly after, my father met his death and I had to face the most important decision of my life. As the eldest son, the fate of our people was in my hands. I told them that I believed in my father's oath, that I truly desired to follow it through, and I would not rest until it was fulfilled and the Silmarils were back in our posession. I told my brothers and my people that I would lead them to glory and victory.
The alternatives were too terrible to consider. The Curse was upon us, that should we fail we would be consigned to everlasting darkness. I saw a glimpse of that darkness on Thangorodrim and it terrified me. So I told the lie, that I would lead my people to glory and victory, and I told it to myself over and over, until I finally convinced myself that it was true, and I really believed that I was doing the right thing.
The consequences - well, you can read about those in the Book
. Almost six hundred years of war, bloodshed, and defeat. The only thing I led my brothers and my people to was their deaths. Ultimately even the geography of Arda itself as changed by the wars we fought. Consequences don't get much more far-reaching than that.