Then Fingon looked towards Thangorodrim, and there was a dark cloud about it, and a black smoke

Then Fingon looked towards Thangorodrim, and there was a dark cloud about it, and a black smoke went up; and he knew that the wrath of Morgoth was aroused, and that their challenge was accepted. A shadow of doubt fell upon Fingon’’s heart; and he looked eastwards, seeking if he might see with elven-sight the dust of Anfauglith rising beneath the hosts of Maedhros. He knew not that Maedhros was hindered in his setting forth by the guile of Uldor the accursed, who deceived him with false warnings of assault from Angband.

But now a cry went up, passing up the wind from the south from vale to vale, and Elves and Men lifted their voices in wonder and joy. For unsummoned and unlooked for Turgon had opened the leaguer of Gondolin, and was come with an army ten thousand strong, with bright mail and long swords and spears like a forest. Then when Fingon heard afar the great trumpet of Turgon his brother, the shadow passed and his heart was uplifted, and he shouted aloud: ‘Utúlie’'n aurë! Aiya Eldalië ar Atanatári, utúlie’'n aurë! The day has come! Behold, people of the Eldar and Fathers of Men, the day has come!’ And all those who heard his great voice echo in the hills answered crying: ‘Auta i lómë! The night is passing!’

–J.R.R. Tolkien, The Silmarillion, “Of the Fifth Battle: Nirnaeth Arnoediad” (Art by Alan Lee)