For questions about Morgoth, also known as Melkor, the first dark lord in J.R.R. Tolkien's Middle-earth universe. This touched off the war of the jewels, detailed in Tolkien's *The Silmarillion*. Always use in conjunction with the [tolkiens-legendarium] tag and any other more relevant tags where appropriate, for example, [the-silmarillion].
Melkor committed several evils, first destroying the two Great Lamps and constructing his fortress Utumno. Destroying these lamps caused widespread destruction, and caused the Valar to retreat to Aman, to Valinor, giving Melkor dominion of Middle-Earth. It was at this time that he corrupted Elves into Orcs. Melkor had many powerful servants and allies, including the second dark lord Sauron, who was his greatest lieutenant, who he put in charge of his second fortress, Angband.
The Valar then attacked, and overcame Melkor, imprisoning him for three ages. Many of his forces, however, simply went into hiding, and when he was finally released, feigning repentance, inciting the rebellion of the Noldor and finally destroying the Two Trees. Melkor used this as a distraction to steal the Silmarils. It was at this time that Ungoliant and he fought, and Feanor renamed Melkor "Morgoth" (Dark Enemy). Morgoth rebuilt Angband and then constructed his new fortress, Thangorodrim.
The war of the jewels then was started, and lasted for many years, and eventually Beren and Luthien were able to recover one of the jewels. Eventually, Morgoth destroyed Gondolin, the Noldor's great realm, completing his triumph, but it did not last. The Valar again came forth and utterly defeated. He was cast into the Timeless Void, where he is to stay. Some of Tolkien's later writings say that Morgoth may return to start the Dagor Dagorath at thee end of the world.