> The Silmarillion
Then Angrod was wrathful and went forth from the council. Maedhros indeed rebuked Caranthir; but the greater part of the Noldor , of both followings, hearing his words were troubled in heart, fearing the fell spirit of the sons of Fëanor that it seemed would ever be like to burst forth in rash word or violence.
Maedhros Maglor Celegorm Caranthir Curufin Amrod Amras
The seven princes of the Noldor are the main driving force behind the biggest perpetrator of the history of the Elves. After their father Fëanor swore his terrible Oath, they jumped by his side and swore the same. After the death of their father in the Dagor-nuin-Giliath, they fortified the lands in east Beleriand where they were generally allied with the Elves there. The Sons remained fairly dormant after the death of their father until they heard the story of Beren and Luthien and their successful recovery of one of the Silmarils. They attacked all the Elves around in hopes of gaining one the the remaining Silmarils, but eventually lost after Eärendil carried the one they sought after back to Aman.
An Oath that none should take and none should break...
They continued their pillaging until the last two remaining brothers, Maedhros and Maglor, stole the last two remaining Silmarils from the camp of Eönwë. Their success was not long lived, as the Silmarils would not tolerate being possessed by them. In their despair, Maedhros cast himself and his Silmaril into a great fissure and Maglor cast his into the Great Sea.
Maglor was the last of the seven Sons of Fëanor and the only one to survive into the Second Age.