Cruiser

A cruiser is the smallest classification of capital ship used by human-dominated organisations such as the UNSC Navy, represented by the hull classification symbol C. Cruisers often form the backbone of most naval formations, with their power and surprising versatility for their size allowing them to act as flagships.

Characteristics
Cruisers are a significant jump up from smaller escorts, and symbolise the massive discrepancy between the capabilities of a capital ship and that of a smaller fleet vessel. While the term may be confused with smaller 'merchant cruisers' and 'stealth cruisers,' the smallest true cruisers weigh no less than six million metric tons in mass, and have a total length of more than a kilometre. Indeed, most modern examples have an operational mass of eight to nine million tonnes. They are armed with spinal cannons whose barrels are longer than most frigates, and mount weapons too large to be mounted on smaller hulls. They are well-protected with 2 - 2.5 metres of armour, although those with 'all-or-nothing' schemes can have more. All cruisers can carry a some sort of fighter wing and ground force, rather than a detachment used solely for security work aboard them. Cruisers can be found in a wide variety of hull configurations and specialisations, as their size means that they are large enough to hold their own without escorts, unlike smaller vessels.

Cruisers are the most powerful spatial combatants available to most squadrons, as they are able to single-handedly destroy or threaten most starships thanks to their assortment of heavy weaponry. They take the lead in most naval operations, and often pursuing objectives that would require an armada of smaller frigates and destroyers to achieve. The exact goals vary, with light cruisers being responsible for countering lighter warships and responding to enemy incursions. Meanwhile, heavy cruisers directly participate in battle, challenging all but the largest vessels in opposing fleets. However, these are not strict roles, and cruisers are seen conducting everything from planetary bombardment to deep-space exploration to niche anti-aircraft deterrence. While not a requirement, the UNSC often uses cruisers as auxiliary command ships, and encourages broken fleets to rally around these ships if disaster befalls their flagship.

Patrol Cruiser
Patrol Cruisers are a now-historical name given to a specific style of spatial combatant that saw service from humnanity's interplanetary period to the UNSC-CMA Cold War. In contrast to modern designs, these vessels are fairly small, and are not that much larger or much more powerful than destroyers or frigates. Instead, these prioritized range over all else, with significant stores of spare parts and consumables to allow them to undertake months, if not years-long deployments. Given their size, they usually host some form of flag deck for coordinating small task forces, though carriers still remain the preferred flagship.

The Patrol Cruisers were completely replaced by the modern cruiser following the introduction of the, whose unprecedented combination of size, firepower, durability, and speed completely eclipsed any spatial combatant design that came before. This sharp change in the mission profile saw all future ships being rebranded as destroyers.