Dagor-nuin-Giliath

After the First Kinslaying and the burning of the Telerin ships, Feanor sought to avenge his father's death by facing Morgoth's armies. Feanor struck a terrible Oath with his seven sons and sought to destroy Morgoth. However, as Namo stated "Even if thou were thrice greater could you not accomplish this."

Feanor led his forces to Beleriand and assaulted Angband in a battle that would become known as "The Battle-Under-Stars." Though the greatest of elves in mind and body fought valiantly against impossible odds, he was wounded by Gothmog and died from the wound. Gothmog would retreat from Feanor's sons, but the battle was lost with Feanor's death.

Eventually Maedhros met with an embassy of Morgoth's and was captured and hung on Thangorodrim. He was eventually freed at the cost of one of his hands--this would spur him to create a council group that was dedicated in ridding the world of Morgoth permanently.