The Shadow-class Frigate is a heavily modified UNSC Frigate combining its firepower with the stealth capabilities of a UNSC Prowler. Their primary function is high profile infiltration and exfiltration to combat zones or ambush. The three ships of this classification were formed into one squadron. Up until September of 2552 they was used primarily for the latter function, until it picked up Codename: REGAN and Sierra-013 from the ruins of Reach. After participating in the Battle of New Anatolia and a brief return to Earth, the squadron continued on various high profile ONI missions.