> The Silmarillion
'But how shall our voices reach to Ilúvatar beyond the Circles of the World? And by Ilúvatar we swore our madness, and called the Everlasting Darkness upon us, if we kept not our word. Who shall release us?'
Maedhros was the eldest of the seven Sons of Fëanor and was considered to be their leader. He was the first to leap to his father's side when he said The Oath of Fëanor and swore it himself. Though he was the quickest of the seven to support his father, he was more temperate than him, but by far not the calmest of all the Sons. When Fëanor proposed the burning of the ships and Losgar, he strongly insisted otherwise.
After Fëanor's death in the Dagor-nuin-Giliath, Maedhros was captured by Melkor and hung by his right wrist from the peaks of Thangorodrim. Though later rescued by Fingon and the Lord of the Eagles Thorondor, he lost his hand. In payment/gratitude for this, Maedhros handed the lordship of the Houses of the Noldor to Fingolfin.
This served greatly to dampen the Oath's affect on him. After this, he dwelt main on the hill of Himring in the northeast of Beleriand, trying to curb the rashness of his brothers and guarding the surrounding area. After the Dagor Bragollach, the Oath finally caught up with him, and he helped in the assaults on Doriath. After this he persuaded his brother Maglor to help him still the two Silmarils in the possession of the Valar and let him claim one as his own.
They succeeded in their quest, but the Silmarils did not allow themselves to be held by such ones tainted by Doom. Percieving this, Maedhros cast himself and his Silmaril into a chasm. Thus ended the tallest and proudest of the Sons of Fëanor and one of the three Silmarils.