Imprisoning War

The Imprisoning War (Seal War in Japan) started after Ganondorf entered the Sacred Realm and laid claim to the Triforce, becoming Ganon and transforming the realm into the Dark World, from which he launched an invasion against Hyrule, prompting the King to summon the Knights of Hyrule and Sages in defense. The Knights fought and eventually perished during the invasion, but delayed Ganon long enough for the Sages to seal him in the Dark World.

The Imprisoning War was first mentioned in A Link to the Past. It was covered in detail in the manual, but the American translation differed in several key places from the original Japanese, making it inconsistent with the story told in other parts of the series.

Ocarina of Time was originally meant to cover the Imprisoning War, but more recent games have cast doubt on whether it actually does depending on how one interprets the series.