Good day fellow Spartans, these ideas for the structure of the post war UNSC fleet is both a mix of in universe ships and created classes. Similar how these ships would be operated in the fleet and their payload, compliment and capability will also be a mix of fact and speculation and my own reimagining. This will be my first post will be about the fighting ships, a second will be supports ships and the last be the secrative fleets of ONI. Happy to have any feedback. So without further delay.

The UNSC fighting fleet consists of 10 classes of warships, 3 classes of support classes, while ONI operates 4 classes of stealth ships. The fighting fleet is broken down with these classes;

INFINTY class. Proposed x3, 8.7km ships of this class, headed by the flagship UNSC Infinity to act as single mass deployment platforms and command ships, each one operating in each of the three teirs of UEG 15 lightyear defensive sphere of controlled space, or leading UEG/ONI directed expeditions for forerunner worlds and tech caches.
This delta version of the Infinity class has been significantly lengthen from its base model, incorporating technologies and lessons learnt from the human covenent war to the most recent created uprising. These include further improved SMACs, installation of Shango directed energy batteries and a hybrid Forrunner/AI matrix.

TRAFALGAR class. Named after the most famous Punic supercarrier UNSC Trafalgar, these 4.2km ships are used as intermediary between the Infinity class and the smaller ships of the fleet. Designated as fleet carriers for mass single craft deployment and battle space control ships, they combine the role of the EPOCH and PUNIC classes before them. Often heading expeditionary forces to restablish UNSC presence. A dozen of these ships are proposed with x2 in service.

POSIDEN class. Short of a kilometre long, these light carriers are out tonned by all of their predecessors, however they make use of all of the post war technologies, including a pair of Mark III Shango directed energy batteries as its primary weapon. Their design and intent is based on a doctrine of rapid strike fleet deployment.
Unlike the larger carriers, Infinity and Cutter classes, which have dedicated forges for construction of single craft, vehicles and a bottomless source of ordinance, Posidens have large, modular sections for holding tailored air and ground engagement groups dependant for quick reaction within their sector. Currently over 80 of this class are in service with the UNSC with scores more planned.

CUTTER class. Named after the fabled captain of the Spirit of Fire, these 2.7km ships serve like their predecessors as the hub for planetary deployment of ground forces and nerve centre of a rapid strike fleet. Improved with post war technologies in fabrication and design, ensure the ships dedicated forges can convert raw materials into tools of war is short order. While enhanced sensors, weapon systems, and series of modular deployment bays, ensures that a single Cutter class can support multiple planetside engagements at any time.

VINDICATION class. These 2km battleships are dedicated to counter enemy capital ships, building from all the experiences gained during the war and perceived future threats. This class housed the same SMAC used by the Infinity class and ODPs along with a comprehensive suite of mini MACs, heavy coil guns, directed energy turrents, oversized missile batteries and CIWS. It's hanger is small for its size, using it to hold dedicated UCAVs for ECM warfare and swarm attack along with a small ODST strike force and transport. It houses two ordinance forges to keep it's batteries well stocked in a fight.

AUTUMN class. These form the bulk of the UNSC ship to ship fighting fleet. Build on the exploits of the upgraded Halcyon class Pillar of Autumn, these ships are primarily used as escorts for the larger capital ships and teeth of any strike fleet with their twin series IX heavy MACS and coligun/ missile batteries. It also possesses a series of large modular deployment bays for ODST and marine airdrops and hanger for supporting strike and transport craft.

IROQUOIS class. The Iroquis class fleet destroyer is a blend of the light cruiser and earlier Halbert class destroyer. It sports pair of MACs, a Mark IV heavy MAC primarily for anti ship engagement supported by a lighter Mark II for delivery of smart ordinance, supply pods, drones and engaging lighter targets. As with many other ships in the fleet, modular mission bays to house tailored air and ground forces are fitted to allow for greater mission flexibility.

STRIDENT class. Build in the hundreds, these frigates form the backbone of the UNSC fleet along with the Anlace class. Their powerful MACs and weapon batteries, energy shielding and operations bay make them potent escorts and rapid strike ships. 

ANLACE class. This frigate is greatly unique in many ways. It is the smallest frigate class ever used by the UNSC. Its adapted for atmospheric actions, though it's effective at ship to ship battles. It also is the first ship class to have a directed energy weapon as its primary weapon, with its MAC used in a secondary role along with its missiles in support of ground forces or ship attacks. It's mission bay consumes a large portion of the ships mass and is almost exclusive in support of planetary ground and airborne actions.

GLADIUS class. Operating as interdiction and patrol ships, these are the smallest class of warship in the UNSC navy. Outgunned by many ships, they rely on their extensive sensor and tracking suites, low profile and high speeds to track and thus avoid hostile ships. They have become favoured strike ships of special operation units for their sensors, compact mission bay and heavy, precise firepower they can bring to bare in support of said teams.

Will post more according to the feedback. Feel free to help critic and ask questions about the ideas about the fleet.
Quote 1 0