The War of Wrath

The First Age is, in the larger context of the vast swaths of time that make up much of the defined eras of Tolkien’s work, pretty short all things considered—instead of existing across thousands of years, it’s just shy of a sprightly six hundred. Many key things happen in the First Age, such as the emergence of Men, as well as the return of the Noldor Elves to what would eventually be the region of Arda known as Middle-earth—known at this point in time as Beleriand—as they pursued Morgoth in vengeance for the destruction of Laurelin and Telperion. Morgoth, meanwhile, has consolidated vast control over much of Beleriand. Having defeated the pursuing Elves and maintaining control of the silmarils, Morgoth began having grander plans to use his hosts of orcs and other primal forces—including Balrogs and the first dragons—to destroy Elves, Men, and Dwarves alike, tightening his grip across the region.
The tide would eventually turn in the final 42 years of the First Age, with the beginning of the War of Wrath. Eärendil, a half-Elven sailor, took the treacherous voyage to Valinor to petition the Valar themselves to aid the mortal races from complete destruction at Morgoth’s hands. Although the Valar had originally been content to let the Noldor who had left Valinor to hunt Morgoth perish, they relented to Eärendil. They put together a mighty host alongside the Elves that had chosen to remain in Valinor, and set forth for Beleriand—where Morgoth amassed all of his forces to try and put a stop to his former celestial allies once and for all.
For as mighty as his own forces were, however, they were no match for the Valar’s host. Uniting with the remaining Elves as well as the three tribes of Men, known collectively as the Edain, the host smashed Morgoth’s orc armies, and even though they themselves were nearly beaten back by the arrival of the dragons, Eärendil matched them with the Great Eagles, beating back the dragons and slaying their leader Ancalagon the Black. Morgoth was captured, returned to Aman in the west, and ultimately tried by the Valar for his endless crimes… which lead to him not only being beheaded, but his body cast out into the void of space beyond Arda itself.