Changing of the World

After Ar-Pharazôn broke the Ban of the Valar by sending an army to Aman to conquer the Valar and obtain immortality from them, the Valar laid down their guardianship of the world and called upon Eru Ilúvatar, who responded with this great cataclysm that forever changed the world.

This series isn't chapter-gated yet, so we can't hide individual spoilers. To keep you safe, everything past the intro stays hidden. If you've finished it, “Show everything” above reveals it all.