The History of Middle Earth

War of Wrath

The Valar were moved by Eärendil's plea, and along with the Vanyar and the remaining Ñoldor in Aman, came to Middle-earth in a mighty host. Of the Teleri of Alqualondë, they granted the use of their ships to the powers of Aman, but none would aid the Ñoldor in Middle-earth, remembering the Kinslaying of their people long ago and were still bitter about it. The great force of Aman marched across Beleriand, and met the terrible forces of Morgoth in the plains of Anfauglith.

The host of the Valar utterly destroyed the Orc armies of Morgoth, as well as most of the Balrogs, with minimal casualties (though in Annals and the Tale of the Years, the passage of the river Sirion are taken by the West only after 40 years of bitter fighting). While the Three Houses of Men fought alongside the Valar, many other Men from the East fought for the forces of Morgoth and were either destroyed or forced to flee back to the far eastern parts of Middle-earth. Facing final defeat, Morgoth, in a last desperate effort, released his ultimate weapon, the winged Dragons, which had never been seen before. Their terrible onslaught was accompanied by lightning storms and tempests of fire, and they drove the Valar back and nearly destroyed the entire force.

Just as it seemed the battle was lost, Eärendil came with his sky-ship Vingilot, along with the Eagles of Manwë led by Thorondor. In the skies above Angband, they contested with the dragons, slaying most of them despite suffering many losses. Eärendil himself slew their captain, the mighty Ancalagon the Black, who broke the towers of Thangorodrim in his fall. (A prophecy given in Athrabeth Finrod ah Andreth in Morgoth's Ring gives the slaying of Ancalagon to Túrin instead). It is not stated how exactly Eärendil managed to slay Ancalagon. This is something of a curiosity considering that Ancalagon's size was great enough to break the three mountains of Thangorodrim when he fell upon them, each of which were stated to be 5 miles across and 35,000 feet high.

Aftermath
Morgoth was finally captured in the deepest dungeon of Angband and bound again with his old chain Angainor; by the Vala Aulë and the two Silmarils still in his possession were taken by the Maia Eönwë, the herald of Manwë and guarded (whence they were later stolen by Maedhros and Maglor and cast into the sea and lost in the Earth) and Morgoth's crown was beaten into a collar for him. He was taken to Aman and tried for his crimes. In the end, the Valar unhoused Morgoth by beheading him and "thrust him", in which his spirit was banished forever in the outside world and universe of Eä