Bound by the Oath of Fëanor, he went to Middle-earth with the host of the Noldor. Shortly after the battle of Dagor-nuin-Giliath in which Fëanor was killed, Maedhros was captured by Morgoth, and hung by the wrist of his right hand upon the face of a precipice of Thangorodrim. Fingon rescued him in a daring feat, helped by Thorondor the King of Eagles, but he had to cut off Maedhros' hand to release him from the shackle.
Maedhros later ruled the lands around the Hill of Himring, which became known as the March of Maedhros because it was exposed to the hosts of Morgoth, and defeated them in the Dagor Aglareb. He later gathered his brothers, other Elves, Men, and Dwarves into the Union of Maedhros, assaulting Angband, but the host was defeated in the Nirnaeth Arnoediad.
Still driven by the Oath, he and his surviving brothers descended with an army on the people of Eärendil living in the Havens of Sirion by the river's mouth, killing many, but Elwing escaped with the Silmaril.
Finally, after the War of Wrath, with his brother Maglor he demanded the two Silmarils taken by the Valar from Morgoth, but when they refused, saying that he had forsaken his rights by his misdeeds, he and Maglor slew the guards and took the jewels. But the Silmaril he had taken burned his hand with unbearable pain, and in despair he ended his life by casting himself into a fiery chasm, taking the Silmaril with him.