UNSC Navy

The UNSC Navy (UNSCN) is the branch of the UNSC Defense Force responsible mostly for naval warfare and operations in space, though they still operate in the oceans with their terrestrial arm. Its roles include ship-to-ship combat; orbital bombardment; the deployment of atmospheric and space fighters, and the delivery of UNSC Marines into combat.

Formation
The UNSC Navy was created during the Interplanetary War of the 2160's—precisely during the Mars Campaign of 2163—as a result of the United Nations' need to oversee and monitor Marine deployments from space, thus forming the United Nations Space Command. After the UN's victory in that war, the UNSC Navy became involved in colonization, the settling of minor trade disputes, and anti-piracy operations as humanity spread through space.

The Insurrection
Such low-level operations continued until the Insurrection, which forced the Navy to develop a modern space warfare doctrine. Beginning with the Callisto Incident of 2494, the UNSC Navy was involved in a series of small but important actions against Insurrectionists across human space. In 2494, the Eridanus Government requested aid from the UNSC when rebels performed a well-planned and efficiently executed terrorist campaign on the planet. This led to Operation: CHARLEMAGNE in January of 2496, when the UNSC Navy responded to the government's requests and began their campaign to retake Eridanus II, deploying a battle group to engage the makeshift Insurrectionist defence fleet. The clandestine activities of the Office of Naval Intelligence also proved to be particularly useful in dealing with Insurrectionists during Operation: TREBUCHET in the Eridanus and Epsilon Eridani systems. The Navy played an important role in the elimination of rebel cells and in engagements of more organized insurgent groups—most notably the United Rebel Front. Other major battles and engagements the UNSC Navy participated in include the Battle of Theta Ursae Majoris and the Skirmish at Capella.

The lessons learned from the space engagements of the Insurrection may have contributed to the UNSC's eventual victory in the Human-Covenant War. From the Insurrection came the Magnetic Accelerator Cannon, titanium-A armor, naval protocols, and advances in ship-to-ship warfare tactics, all of which would prove crucial in humanity's fight against the Covenant. Furthermore, the Insurrection also saw the beginning of the career of Preston Cole, who would make an enormously decisive commitment to the Human-Covenant War.

Human-Covenant War
Prior to the Human-Covenant War, the UNSC Navy had a large fleet of warships, including many capital ships and single-ship craft. However, beginning with the near-total destruction of the Colonial Military Administration's Battlegroup 4 at the First Battle of Harvest, followed by the loss of thirteen out of forty ships at the Second Battle of Harvest, the UNSC Navy sustained heavy losses of matériel and personnel throughout the war against the Covenant. Going on the offensive from 2526 to 2543, the bulk of the UNSC Navy under Admiral Preston Cole fought a series of victorious but enormously costly actions against the Covenant fleet.



At the Battle of Alpha Aurigae in the Origami Asteroid Field in October 2526, a total of 117 UNSC naval vessels defeated the Covenant's twelve—at least three of which were s. However, thirty-seven UNSC ships were lost. The Battle of XI Boötis A in 2528 saw the loss of thirty ships out of the UNSC's seventy to the Covenant. The Battle of the Great Bear at the Groombridge 1830 system in 2530 saw eleven destroyers out of the fleet of seventeen destroyed by three enemy ships.

By 2536, the Covenant had begun to encroach on humanity's Inner Colonies. To prevent the Covenant from discovering more human colonies or Sol itself, Admiral Preston Cole established the Cole Protocol. The protocol forbade retreating vessels from setting a direct slipspace course toward any colony and dictated the destruction of navigation data on Covenant-captured naval ships. Every shipboard commanding officer in the Navy was ordered to read the new protocol. Some naval vessels, such as, were ordered to patrol UNSC space to enforce to Cole Protocol. In 2543, the UNSC Navy scored one final offensive victory against the Covenant at the Battle of Psi Serpentis, though at the cost at the apparent death of Preston Cole.

In 2552, the Navy scored a morale-boosting victory at Sigma Octanus IV, but this was quickly offset by the crippling military losses of the Fall of Reach and the Battle of Tribute. The Navy lost over a hundred ships, including irreplaceable cruisers and supercarriers such as the, , and the at Reach,  and lost ninety percent of naval assets at Tribute. In the same year, a very large portion of its remaining ships were lost when the Prophet of Truth's military forces occupied Earth. As a result, the UNSC Navy was only able to make a contribution of three frigates to the Battle of Earth and the Battle of Installation 00, with the Sangheili navy handling most of the space fighting.

Post-war
In the aftermath of the Human-Covenant War, the Office of Naval Intelligence began operations to sow dissent amongst the Sangheili, disregarding their wartime alliance in the hopes of rendering them unable to fight should they become a threat again. Among this operation's effects was the beginning of the Sangheili civil war and the establishment of a Covenant remnant led by Jul 'Mdama. While the former Covenant fleet's naval vessels fell into the hands of various splinter factions established by the former client species, the UNSC Navy began to rebuild and continued to grow.

In early 2553, the Navy launched its most powerful warship, the, though she would not be officially commissioned for another four years. Built in secret using technology recovered from Forerunner and Covenant sources during the war, the Infinity is the UNSC's largest and most advanced warship to date. In March 2553, she secretly intervened in the Sangheili civil war, and demonstrated the UNSC's new technical capabilities by easily destroying the Covenant destroyer Defender of Faith.

In 2557, the Infinity distinguished herself during the First Battle of Requiem and the recovery of Master Chief Petty Officer John-117. The UNSC Navy's forces around Earth had also been rebuilt, and the Home Fleet defended the planet against the Didact when he arrived with the intention of digitizing all of humanity with the Forerunner weapon known as the Composer. Earth's orbital platforms and the Home Fleet's Battlegroup Dakota had little to no effect against the Didact's ship, the Mantle's Approach, but the Infinity managed to damage the ship, allowing John-117 to enter using an F-41 Broadsword and destroy the ship with a HAVOK tactical nuclear weapon. The fighting continued six months later with the Infinity's second expedition on Requiem.

Command and control
The UNSC Navy is subordinate to the UNSC High Command (HIGHCOM). The Navy is administered by the UNSC Naval Command, or NAVCOM, headed by the Chief of Naval Operations, which in 2558 was Fleet Admiral Lord Hood. The CNO is assisted by the Deputy Chief of Naval Operations. NAVCOM is split into three commands; Fleet Command, or FLEETCOM, has oversight of ship deployment, mission structures, and space operations, including the transport of troops and naval fighter operations. Logistical Operations Command, or NavLogCom, oversees the construction, maintenance, and distribution of supplies and matériel, including ships, ammunition, replacement parts, and food. Naval Special Warfare Command, or NAVSPECWARCOM, and Naval Special Weapons (NAVSPECWEP) are responsible for all Naval special operations, including deployments of SPARTAN-IIs. The UNSC Navy also operates Central Commands (CENTCOM) which hold responsibility over a certain area of space. A CENTCOM commander has the authority to blockade a system, or aid in the coordination of a battle occurring within the regional space they command. UNSC and UEG space is further divided, governed, and protected by the Navy's Fleet Command sectors which each contain a number of planetary systems.

The Office of Naval Intelligence is technically subordinate to the UNSC Naval Command. In practice, however, ONI's activities extend far beyond intelligence gathering, and it often receives mandates and directives from HIGHCOM or even higher. ONI holds a strong presence in the UNSC fleet and maintains joint control of the Navy's post-war flagship,. Despite being under the command of the Navy, ONI's Commander-in-Chief holds a seat on the Security Council with equal stature and privilege to the committee members of the Navy, Marines, Army, and Air Force.

Commanding positions in NAVCOM tend to be held by admirals. Because of their role as an "amphibious", space-deployed force, the UNSC Marine Corps enjoys a close relationship with the Navy, with Marine complements being deployed on most warships.

Operating forces
UNSC Navy forces are divided into a number of fleets. These tend to be large formations, though they seldom patrol together; single ships are commonly seen patrolling throughout UNSC space. System fleets, such as the UNSC Home Fleet or the Epsilon Eridani Fleet, are commonly formed to patrol and defend a human colonized-system. More common tactical formations are battle groups, which are formed on an as-needed basis and vary dramatically in size from three ships to large carrier groups.

The UNSC Navy also has several numbered fleets, four of which were active during the Human-Covenant War—the Second, Third, Fifth, Seventh, and Sixteenth Fleets. These fleets are further divided into several battle groups.

Seaborne forces
Into the 26th century, the UNSC Navy continued to use maritime ships to patrol the seas. Little is known about this Naval arm. It is known, however, that Earth and the fortress world of Reach had bases for it. Other than that, it is known that the Navy possessed numerous aircraft carriers with full complements of F-99 Unmanned Combat Aerial Vehicles, suggesting that they were constantly kept at a high level of alert.

Other than participating to some extent during the Battle of Mombasa, the wet Navy may have been involved with the operation to the Yucatan Peninsula, where the SPARTAN Blue Team attacked and destroyed a Covenant excavation force on the sea floor of the Gulf of Mexico.

Personnel
Large numbers of men and women are employed by the UNSC Navy. Servicepeople hold ranks, which are divided between officers and enlisted. UNSC Navy personnel are given training in self-defense. All crewmen are trained to use the M6 series of handguns. Naval personnel are sometimes referred to as "swabbies", which can be a joke or a sign of disrespect. Navy recruits serve in initial recruit training operated by the Unified Combined Military Boot Camp. At boot camp, recruits are trained, tested, and evaluated on their physical fitness, proficiency with firearms, and command potential. Following graduation from UCMB, a naval recruit may be required to complete additional training revolving around the vacuum of space and microgravity. Finally, a recruit is assigned aboard a naval vessel or installation as a non-commissioned recruit within the Navy. Several human colonies are home to Officer Candidate Schools that provide training and allows enlisted personnel or civilians to become officers. Renowned OCS academies include the Luna OCS Academy and the Corbulo Academy of Military Science.

UNSC Navy personnel wear distinctive uniforms for identification, comfort, and practicality. Dress uniforms are worn on formal occasions, such as ceremonies and other official functions, while service and working uniforms are the basic uniform worn by UNSC Naval personnel while on duty.

A full list of Naval personnel can be found here. For a list of ranks within the UNSC Navy, see UNSC rank structure.

Weapons
The primary offensive armament of UNSC spacecraft is the Magnetic Accelerator Cannon (MAC). These are high velocity coil guns that are used to accelerate projectiles ranging in mass from 600 metric tons in the case of smaller warships, and 3,000 tons in the case of Super MAC platforms. These projectiles are composed of titanium, depleted uranium, or tungsten with a ferrous core. "Super MAC" Orbital Defense Platforms accelerate MAC rounds to "point four-tenths" the speed of light, around 12,000 kilometers per second, with twenty-three linear accelerator coils, while ship-based MACs have a lower velocity. Super MAC platforms can also reload a round in five seconds, where as ships will need several minutes to charge their MAC coils.

The UNSC frigate Gettysburg is quoted as firing a 600 ton shell at 30 kilometers per second. Before Reach fell, the was equipped with a modified MAC that could quickly fire three lighter projectiles in succession instead of just one heavier projectile. It was originally intended to allow the Pillar of Autumn a better chance of disabling a Covenant ship, which was a feature required for a mission that was later scrubbed following the Fall of Reach.

Almost all UNSC warships are equipped with M58 Archer missile pods for ship-to-ship engagements, which prove most effective against unshielded targets. A common tactic among UNSC ships is to disable the target's shields with MAC rounds and then pummel it with Archer missiles. In 2525, UNSC ships carried fusion missiles as an offensive weapon. They seem to have been removed or replaced in later years. UNSC ships may also carry Shiva-class nuclear missiles. In addition, the UNSC mounts 50mm auto-cannons on its ships for defense against enemy fighters and boarding craft, controlled by shipboard AIs.

UNSC warships also carry significant Marine detachments for internal security, boarding actions, and planetary assault, and carry all the equipment and matériel needed by Marine forces. It is implied that a significant portion of the interior of UNSC warships are devoted to this purpose, as there are armories and barracks that hold these supplies.

Ships of the UNSC Navy also carry a number of GA-TL1 Longsword interceptors. These are armed with 110mm rotary cannons and ASGM-10 missiles, and sometimes a Moray space mine system or even a single Shiva-class nuclear missile. They can also be remotely-operated and used to carry a remotely-detonated Shiva missile, which, when detonated, effectively destroys both the Longsword and its selected target.

Despite all of this firepower, however, UNSC warships during the Human-Covenant War had great difficulty in defeating Covenant ships even with a numerical advantage. It typically took multiple hits from a ship-based MAC weapon to disable a Covenant ship's shields, although larger, ODP-based "Super MACs" fire a round that can literally shatter Covenant capital ships. Archer missiles had to be used in tremendous volumes to breach Covenant shield systems. Even with their shields down, Covenant ships have been noted to remain operational after multiple direct hits from normal MAC rounds. This advantage in firepower and shielding gave the Covenant an effective 3:1 ratio and better against UNSC ships as of the Human-Covenant War.

Ships
UNSC Navy vessels are typically armoured with Titanium-A armor; such protective armor remained the defensive standard of UNSC vessels until they were further reinforced with the introduction of energy shielding in the post-war era. The largest vessels of the UNSC fleet are carriers and supercarriers. While possessing weapons of their own, their primary role is to deploy fighter craft such as the GA-TL1 Longsword, and may serve as flagships in fleet actions. If a carrier is unavailable, however, then heavily-armed and armored cruisers may fill this role. The current flagship of the UNSC Navy is the, the first of the Infinity-class vessels which make use of defensive and offensive advances reverse-engineered from both Forerunner and Covenant technologies, with the specific intention of matching Covenant warships in terms of offensive firepower. The UNSC Navy has operated four known classes of cruiser; the, the , the now-obsolete , and the postwar.

UNSC destroyers and frigates of various classes are used for escorting larger cruisers and carriers, as well as for independent patrol and scouting operations. Both are roughly the same size, but destroyers are designed with greater emphasis on firepower and armor over versatility. Frigates are multi-purpose warships that are used in a broad range of roles, ranging from heavy air support to fighter escort and fleet engagements. Some UNSC frigates are equipped with a sizeable cargo bay for larger dropships and armor complements. The UNSC has also employed light frigates equipped with stealth systems in a specialized reconnaissance role.

The Navy maintains a wide variety of smaller craft and support ships. These include prowlers for electronic intelligence gathering, refit stations, exfiltration craft, shuttles, and corvettes. Corvettes are notable as being one of the fastest ships in the UNSC Navy, and a number of sub-classes have been developed including the Mako-class and the fast-attack corvette.

At least some UNSC ship production is handled by the Reyes-McLees Shipyards over Mars, though this may no longer be true due to the Covenant invasion of the Sol system in 2552. Additionally, SinoViet Heavy Machinery manufactured and decommissioned s on Reach prior to the Fall of Reach.

Space fighters
Space fighters are small, maneuverable spacecraft, often used for bombing or "dog fighting" in space or in an atmosphere. The UNSC Navy operates a number of fighters, the most common of which is the GA-TL1 Longsword. The Longsword is a multi-role fighter that can be used in a variety of missions, including ground support, anti-ship attacks, and combat with other fighters.

The F-41 Broadsword is a multirole space fighter in use after the Human-Covenant War. Like the Sabre, the Broadsword is equipped with energy shielding that covers the entire fighter and recharges when depleted. However, these shields are not rated for slipspace travel. The Broadsword is equipped with two M1075 ASW/AC 35mm MLA cannons and two M6088 ST/MMP missile pods. The fighter can also be equipped with a single piece of heavy ordnance, such as a HAVOK warhead.

A less common UNSC fighter is the OF92/EVA "Booster Frame". The Booster Frame is an experimental fighter developed as a prototype. They are specifically designed for extra-vehicular activity and special operations roles, dropped from hooks within the hangars of specialized UNSC ships. The fighter itself has no sealed cockpit, so a pressurized suit must be worn in order to operate the vehicle.

Carriers

 * - Status unknown
 * - Status unknown
 * - Epoch-class - Status unknown
 * - Status unknown
 * - Destroyed
 * - Orion-class - Status unknown
 * - Poseidon-class - Status unknown
 * - Destroyed
 * - Supercarrier - Destroyed

Cruisers

 * - Status unknown
 * - Halcyon-class - Destroyed
 * - Halcyon-class - Destroyed
 * - Marathon-class - Destroyed
 * - Autumn-class - Active
 * - Valiant-class - Status unknown, presumed destroyed
 * - Halcyon-class - Status unknown
 * - Marathon-class - Destroyed
 * - Marathon-class - Destroyed
 * - Marathon-class - Status unknown, presumed destroyed
 * - Marathon-class - Status unknown
 * - Heavy cruiser - Destroyed
 * - Halcyon-class - Destroyed
 * - Autumn-class - Active
 * - Marathon-class - Destroyed
 * - Halcyon-class - Status unknown
 * - Marathon-class - Status unknown
 * - Autumn-class - Active
 * - Heavy cruiser - Status unknown
 * - Autumn-class - Active
 * - Valiant-class - Status unknown
 * - Heavy cruiser - Destroyed

Destroyers

 * UNSC Agincourt - Destroyed
 * - Status unknown
 * - Destroyed
 * - Status unknown
 * - Status unknown
 * - Status unknown
 * - Diligence-class - Status unknown
 * - Destroyed
 * - Destroyed
 * - Status unknown
 * - Halberd-class - Status unknown
 * - Halberd-class - Destroyed
 * - Halberd-class - Status unknown, heavily damaged
 * - Hillsborough-class - Status unknown
 * - Destroyed
 * - Halberd-class - Status unknown, presumed destroyed
 * - Status unknown, heavily damaged
 * - Dilligence-class - Status unknown
 * - Status unknown, presumed destroyed
 * - Status unknown
 * - Destroyed
 * - Active
 * - Status unknown, likely destroyed
 * - Halberd-class - Status unknown
 * - Status unknown
 * - Status unknown, moderately damaged
 * UNSC Tharsis - Destroyed
 * - Status unknown, moderately damaged

Frigates

 * - Charon-class - Status unknown
 * UNSC Agincourt - Destroyed
 * - Destroyed
 * - Active
 * - Captured by rebels
 * - Destroyed
 * - Paris-class - Active
 * - Charon-class - Status unknown
 * - Charon-class - Destroyed
 * - Paris-class - Heavily damaged, later decommissioned and scrapped
 * - Destroyed
 * - Status unknown, presumed destroyed
 * - Destroyed
 * - Charon-class - Destroyed, rear section crashed on Requiem.
 * - Paris-class - Status unknown
 * - Paris-class - Destroyed
 * - Stalwart-class - Destroyed
 * - Status unknown
 * - Stalwart-class - Status unknown, presumed destroyed
 * - Stalwart-class - Status unknown, heavily damaged
 * - Destroyed
 * - Paris-class - Status unknown, presumed destroyed
 * - Destroyed
 * - Status unknown
 * - Status unknown, presumed destroyed
 * - Paris-class - Status unknown
 * - Paris-class - Destroyed
 * Stalwart-class - Status unknown
 * - Strident-class - Active
 * - Status unknown
 * - Status unknown, moderately damaged
 * Unidentified frigate (Algolis) - Charon-class - Status unknown

Prowlers

 * - Sahara-class - Active
 * - Destroyed
 * - Status unknown
 * - Status unknown
 * - Destroyed
 * - Active
 * - Eclipse-class - Active
 * - Status unknown
 * - Status unknown
 * - Status unknown
 * - Razor-class - Active
 * - Status unknown
 * - Status unknown
 * - Somewhere in deep space commandeered by 343 Guilty Spark
 * - Sahara-class - Active
 * - Status unknown
 * - Status unknown
 * - Winter-class - Active

Corvettes

 * - Status unknown
 * - Status unknown
 * - Status unknown
 * - Status unknown
 * - Active
 * - Status unknown
 * - Active
 * - Status unknown

Colony ships

 * - - Status unknown
 * - Modified Phoenix-class - Missing in action; adrift in space
 * - Phoenix-class - Scrapped
 * - Status unknown
 * Unidentified colony ship - Present at re-terraformed Reach

Command ships

 * - Infinity-class, experimental starship - Active
 * - Vindication-class - Status unknown

Other ships

 * - ONI special service vessel, destroyed
 * - Unknown class, destroyed
 * - Unknown class, heavily damaged
 * - Unknown class, destroyed
 * - Unknown class, destroyed
 * - Unknown class, active
 * - Unknown class, destroyed
 * - Auxiliary ship, active
 * - Unknown class and fate
 * - Unknown class and fate
 * - Unknown class, destroyed
 * - Unknown class, active
 * - Unknown class, presumed active
 * - Unknown class, active
 * - Cargo ship, unknown
 * - Unknown class, destroyed and repurposed
 * - Auxiliary ship, active
 * - Unknown class, destroyed
 * - Unknown class, destroyed
 * - Unknown class and fate
 * - Unknown class and fate
 * - Unknown class and fate
 * - Unknown class and fate
 * - Science vessel, destroyed
 * - Unknown class, active
 * - Unknown class, destroyed
 * - Unknown class, destroyed
 * - Unknown class, scrapped
 * - Unknown class and fate
 * - Unknown class, destroyed
 * - Unknown class, destroyed
 * - Cargo freighter, unknown
 * - stealth cruiser - Active
 * - Unknown class and fate
 * - Unknown class, destroyed
 * - Stealth ship, unknown
 * - Unknown class, destroyed
 * UNSC Tharsis - Unknown class, destroyed
 * - Unknown class, active
 * - Unknown class, destroyed
 * - Unknown class, destroyed
 * - Unknown class, active
 * - ONI sloop, status unknown
 * - Unknown class, destroyed
 * - Unknown class and fate
 * ONI PRO-49776 - Status unknown
 * Beatrice - - Decommissioned, later acquired by Eridanus rebels and destroyed
 * Coda - Shuttle, destroyed

Civilian craft in temporary commission

 * Long Time Coming - Prospecting ship, destroyed
 * Mona Lisa - Prison ship, destroyed
 * Han - Diplomatic shuttle, status unknown

Orbital Defense Platforms

 * Cairo Station - Heavily damaged
 * Athens Station - Destroyed
 * Malta Station - Destroyed
 * Nassau Station - Status unknown
 * Oaxaca Station - Intact

Other orbital facilities

 * Gamma Station - Orbital drydock, destroyed

Mobile stations

 * - Refit/repair facility, destroyed
 * Station Delphi - Shipyard, decommissioned
 * - Hospital ship, status unknown
 * Anchor 9 - Status unknown, presumed destroyed

Remote scanning outposts

 * Fermion - Destroyed
 * Democritus - Status unknown
 * Archimedes - Active
 * Tripoli - Status unknown

Medical stations

 * ONI Medical Facility - Status unknown, presumed destroyed
 * M25L Recovery Station - Status unknown
 * Lockhart medical station - Active

Trivia
As with the rest of the UNSC military, the structure and many of the traditions in the UNSC Navy are based on those in the United States Navy.

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * Halo 2
 * Halo Graphic Novel
 * Halo: Ghosts of Onyx
 * Starry Night
 * Believe
 * Diorama
 * Halo: Landfall
 * Arms Race
 * Halo: Uprising
 * Halo 3
 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo Wars: Genesis
 * Halo Wars
 * Halo: Helljumper
 * Halo 3: ODST
 * Halo Legends
 * Babysitter
 * Homecoming
 * Origins
 * Prototype
 * The Package
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Blunt Instruments
 * Dirt
 * Headhunters
 * Palace Hotel
 * Pariah
 * Stomping on the Heels of a Fuss
 * The Impossible Life and the Possible Death of Preston J. Cole
 * The Mona Lisa


 * Halo: Blood Line
 * Remember Reach
 * Birth of a Spartan
 * Deliver Hope
 * Halo: Reach
 * Halo: Fall of Reach
 * Boot Camp
 * Covenant
 * Invasion
 * Halo: Glasslands
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: Primordium
 * Halo: The Thursday War
 * The Commissioning
 * Halo 4: Forward Unto Dawn
 * Scanned
 * Halo 4
 * Spartan Ops
 * Halo: Silentium
 * Halo: Spartan Assault
 * Halo: Initiation
 * Halo: Escalation
 * Halo: Mortal Dictata
 * Halo: Nightfall
 * Halo 2 Anniversary
 * Terminals
 * Halo: New Blood
 * Hunt the Truth
 * Halo 5: Guardians Spartan Locke Ad
 * Halo 5: Guardians Master Chief Ad
 * Hunt the Signal
 * Halo: Spartan Strike
 * Halo: Fleet Battles
 * Halo: Last Light
 * Halo 5: Guardians