From Halopedia, the Halo wiki
Teribus Island was an island on the human colony world of Eridanus II in the Eridanus system.
In 2524 a unit of Colonial Military Authority personnel including Gage Yevgenny, Felicia Sanderson and Eric Santiago carried out a raid on an Insurrectionist camp on the island. They arrived to find the rebels had just abandoned the camp because someone, likely in their very unit, had called ahead to warn them. Instead the CMA troops had a barbecue on the beach that night.