UNSC Hermes II
From Halopedia, the Halo wiki
The UNSC Hermes II was a UNSC vessel. In a promotional transmission for Halo: Combat Evolved featured on Bungie's website, the Hermes II received a message from the Covenant Ester-pattern armored frigate, Contrition.
Little information about this vessel exists; it is even possible that the Hermes II was a station rather than a ship. However, it is referred to as an "SCS" class ship, the same letters associated with the UNSC Pillar of Autumn. Therefore, it is possible that the Hermes is a Halcyon-class light cruiser.
Below is an excerpt from the Transmissions that involved the Hermes II:
Through war we will teach your heresy.