The Great Calamity is an event from The Legend of Zelda: Breath of the Wild. This event serves as the main historical context of the game. It corresponds to the disaster caused by Calamity Ganon throughout Hyrule that occurred one hundred years ago before Link awakens from his long sleep inside the Shrine of Resurrection. After he awakens and leaves the Shrine, he thus discovers a ruined Hyrule, in particular through several ruined locations such as the Temple of Time, and a Hyrule Castle controlled by Calamity Ganon.
One century, before Link's awakening from his long sleep inside the Shrine of Resurrection of the Great Plateau, Hylians discovered the ancient relics of the Sheikah constructed ten thousands years prior, including the Guardians and the four Divine Beasts, used to watch over the Hyrule lands. This discovery event coincided with the prophecy about Ganon's return, thus King Rhoam and the Hyrule people decided to create a group of warriors and protectors, the Champions.
Commanded by Princess Zelda, their ranks included Link, her knight and personal bodyguard, and a representative of each major race of Hyrule: Revali of the Rito, Daruk of the Gorons, Mipha of the Zora, and Urbosa of the Gerudo. While the other Champions piloted their race's respective Divine Beast, Zelda was sent on a pilgrimage under Link's protection, praying to statues of the goddess Hylia for the power to defeat Calamity Ganon.
With the help of the Sheikah's Guardians and the Divine Beasts, the people of Hyrule prepared for the return of Calamity Ganon. During this time, the Champions bonded with each other, with Zelda growing especially fond of Link once she realized their similarities as people burdened with tremendous legacies to live up to. However, Zelda was unable to unlock her power in time, and Calamity Ganon proved to have learned from its previous defeat; using its nigh-limitless dark power, it killed the pilot champions, took control of the Guardians and Divine Beasts, and nearly killed Link.
However, Zelda saved Link from the fatal blow, finally unlocking her power. Link was then sent to the Shrine of Resurrection on the Great Plateau, where he would recover in a deep sleep for the next one hundred years. Zelda returned the battle-damaged Master Sword to its pedestal in front of the Great Deku Tree, then used her power to seal Ganon and herself within Hyrule Castle.
Zelda's power has dwindled over the past century, putting Hyrule at risk of Calamity Ganon's return. Everyone hopes Link to recover, reawaken and regain his memories in order to free the spirits of the Champions, reclaim the power of the Divine Beasts, proceed to defeat Calamity Ganon, free Zelda from the depths of Hyrule Castle and save the world from immediate destruction.
- It is possible, although not clear, that this may be what caused Link's death in the possible "Hero Dies and Fall" of Hyrule timeline that splits from Ocarina of Time.
- This also may be a new installation that splits either much earlier or much later in one of the other timelines.