Bandersnatch

Bandersnatch was a UNSC emergency code. Used right after combat operations or disasters have taken place, the code stands for a radiological- or energy-based disaster.

This code has been used many times, most often when a UNSC colony world has been glassed by Covenant forces. It was also used during the destruction of the Far Isle colony due to massive rebellion, and during The First Battle of Earth, after a Covenant Assault Carrier entered Slipspace in Earth's lower orbit and destroyed the city of New Mombasa.

Trivia

 * The word "bandersnatch" comes from the famous poem Jabberwocky.