Oath of Feanor

The Oath of Feanor is when the Silmarils get stolen, Feanor swears that he will get them back. He leads his people through a lot of dangers, including an icy pass. A lot if his people die. He ends fighting a battle, and gets mortally wounded. He then passes the oath onto his sons' heads. They spend the rest of the book in a long war, recover the Silmarils, and then the Silmarils drive them mad. Maedhros kills himself and his brother throws one in the sea.