|This article, Kusanagi-Class Stealth Frigate, is currently under active construction.|
Prowlers fill a vitally important niche within the UNSC Navy - they are able to covertly gather a wide range of intelligence types on enemy fleet movements, communications, and locations, and interpret and provide that intelligence to FLEETCOM for analysis. In combat, they can engage in electronic warfare operations, jamming Covenant targeting systems and sensors, guiding UNSC missiles to their targets, and providing an up-to-the-minute picture of the battlefield for the Fleet. The only limitation is their size - previously, stealth features were only truly feasible on ships approximately corvette-size. Technically, it was possible to refit a frigate for stealth, but the disadvantages meant that these were isolated instances - the exorbitant costs of constructing and maintaining such ships meant that they payoff was small. The only stealth frigate that saw any success, the Midsummer Night, was retired soon after entering service because it was simply beyond the Navy's budget to repair and refit her to return to active duty.
The advances made late on the war, and afterward, rendered this size limitation a moot point. The development of the Tarnhelm metamaterial in particular meant that much larger ships could be retrofitted with stealth capabilities, allowing the Office of Naval Intelligence to field a much wider array of stealth craft for different missions. Prowlers would still serve as the primary stealth ship of the Prowler Corps, but the Kusanagi-Class Stealth Frigate was developed to make use of UNSC stealth in situations that Prowlers were less useful - covert troop insertions, battlefield electronic warfare, and orbital support. During the War of Vengeance, and the Battle of Unmoving Virtue in particular, the Kusanagi's would prove one of the most capable warship designs to enter service in the UNSC Navy, proving themselves in a dozen combat theatres.
While technically still a part of the Navy, the Office of Naval Intelligence's Prowler Corps usually operates its ships entirely separately, responding and answering to its own chain of command. This has been a cause of considerable enmity within the Navy - while the effectiveness of ONI prowlers is undeniable, the problem is that that ONI is often reluctant to commit such rare and valuable ships to combat operations for fear of losing any of them. This is not an unreasonable worry - the cost of constructing and maintaining a Prowler is tremendous, and a considerable amount of ONI's budget is put aside for the task. Losing even one in battle is costly - not just in terms of resources, but also in terms of lives and capabilities. Prowlers allow the UNSC to keep their eye on targets otherwise unassailable, such as high-value Covenant shipyards and worlds, provide intelligence on enemy fleet or troop movements, and otherwise serve as ONI's eyes in the field. Without them, ONI's is blind - and without them, the Navy would be denied crucial capabilities.
Nevertheless, there are some operations where a stealth ship is simply a neccessity. Before the end of the Human-Covenant War, these operations were often hampered by ONI's unwillingness to commit - the Admiralty had learned from these experiences - under Vice Admiral Jeremy Harkon, the Navy embarked upon Project: SHADOW FURY, intent on developing stealth ships for the regular service. Two designs were proposed - XSCS-552, what would eventually become the prototype for the Hektor-class stealth cruisers, and XFF-441, the prototype for the Kusanagi-class stealth frigate. Both were approved, and production of them was swift. By 2552, seven Kusanagi-class ships had entered service, with another seventeen hulls laid down, outstripping the bulkier Hektor-class ships. The Covenant invasion and subsequent glassing of Reach saw ONI forced to destroy the orbital shipyards, with the loss of all the under-construction Kusanagi-class ships, in addition to other ships docked there, but the sevan that were already in service saw combat at the Battle of Earth, and the Mandorla Campaign, acquitting themselves well against enemy ships.
After the war, ONI attempted to incorporate the ships into their Prowler Corps. The final battle had devastated their own stock of stealth ships, and the Kusanagi's had successfully proven themselves in battle. FLEETCOM was having none of that, however - the Kusanagi's were attached to dedicated long-range reconnaissance battlegroups, serving the role that the Navy had always envisaged for a stealth warship, allowing regular Prowlers to conduct more conventional intelligence gathering operations. ONI were not impressed, and further petitions were made, and continue to be made.
During the War of Vengeance, the Kusanagi's were part of the defence forces orbiting Futhark , participating in the battle to defend the human colony against a Blood Covenant strike group. The stealth ships had originally been transferred to that sector because of Jackal piracy on UNSC Merchant Marine ships, intended as invisible escorts and deterrents against the privateers. Instead, they found themselves supporting the ground forces on the planet as the Blood Covenant landed troops and armoured support on the planet. The many design innovations they incorporated served them well - working with the rest of the fleet, the Kusanagi's were able to devastate the Brute ground forces using their improved THOR Weapon System, provide friendly and hostile troop movements and positions to UNSC Marine Corps and Army ground forces, and intercept a number of smaller ships attempting to circumvent the orbital perimeter. At least one Kusanagi, the UNSC Kampilan, was part of the UNSC response fleet that arrived at Ketesh, deploying a team of ODST's from orbit to retake the base of the Orbital Shipyards, working alongside the Voltakran Legion. After the recapture of the shipyards, the Kampilan continued to provide assistance to ground forces, including orbital strikes and dropships support.
The success of the Kusanagi-class stealth frigate saw more of the design commissioned, and though in less numbers than originally planned, the Kusanagi-class ships became a permanent part of the Navy's reconnaissance battlegroups. There exists some enmity between Kusanagi captains and Prowler captains - the former believe that ONI is trying to hoard stealth technology to itself, while the latter believe that the regular Navy is misusing expensive and classified stealth assets.
- "Look at one of the original Prowlers, then look at this. The Kusanagi-class ships have size, firepower, manoeuvrability, and stealth. The only reason ONI keeps the Prowlers in service is because FLEETCOM won't let it have the Kusanagi's. That's not to say they should - they're designed for different roles, even if the differences are subtle."
- "The upper bow hull looks strange, doesn't it? We don't usually use curves much on our ships. It houses the sensors and AI core compartments, and improves deflection of space debris - it needs it, without a shield or even a CEMPF. They interfere with the stealth, apparently. The only protection it has is it's invisibility."
- "Not very well armed for a Frigate, but the THOR makes it the best friend of every ground pounder in the UNSC. Being able to launch a kinetic bombardment strike without the enemy knowing about it until it's too late is what I call fire support!"
- "At first, I thought it was one of our ships - surely it was too sleek to be a human vessel? That was my only glimpse of it - and then I heard the Fleet Master attempt to hail the human Ship Master, and my shock was compounded - it had even disappeared from our sensors. Even the luminary was blinded."