The Massacre at Eridanus Secundus was a Covenant attack on a rebel facility within a series of asteroids in the Eridanus system in late 2552.

Operation: FIRST STRIKE was a mission undertaken by John-117 and several other Spartan-IIs to infiltrate and destroy the Covenant space station Unyielding Hierophant and associated armada of over 500 warships in the Tau Ceti system prior to the Covenant's invasion of Earth.