UNSC Navy (Earth-5875)

The UNSC Navy (UNSCN) is one of the branches of the UNSC Armed Forces, being responsible for naval and orbital warfare and operations. Among these operations are ship-to-ship combat, orbital bombardment, atmospheric and space fighter development, as well as the deployment of UNSC Marines.

Interplanetary War
The UNSC Navy was formed during the Interplanetary War, during the Mars Campaign with the National Security Act of 2163, resulting of the United Nations' necessity of overseeing and monitoring orbital Marine deployment, anti-piracy operations, trade disputes and space colonization.

Insurrection
The UNSC Navy continued fulfilling its low-level operations until the start of the Secession, forcing them to adapt and develop an increasingly advanced warfare, both in doctrine and technology. Starting with the Callisto Incident in 2494, the Navy became involved in numerous strikes against the various Insurrectionist cells and groups that encompassed human space. In 2494, the Republic of Eridanus II from the UEG following a long-planned terrorist campaign on Eridanus II, which led to Operation CHARLEMAGNE in January 7th, 2896, starting a campaign to retake the planet from the Insurrectionists. ONI and its illegal operations was also pivotal to dealing with the rebels through Operation TREBUCHET in both Eridanus and Epsilon Eridanus systems. In conjunction with the Army, the UNSC Navy played key roles into eliminating the Insurrectionist cells and severely weaken the more organized rebel groups, such as the United Liberation Front, with other important engagements such as the Battle of Theta Ursae Majoris and the Skirmish at Capella proving to be decisive wins, although at heavy costs of life.

Numerous weapons of mass destruction were developed during this period, such as the Magnetic Accelerator Cannon, titanium-A armor and the advancement of ship-to-ship combat tactics. Among the heroes of this era came Preston Cole, who rose to become one of the highest-ranking officers of the Navy and a war veteran of the upcoming First Contact War.

First Contact War
Before the First Contact War begun, the UEG was recovering from the mass death and political breakthrough caused by the Insurrection, although the UNSC Navy possessed a large fleet of ships, containing thousands of capital ships and space fighters. However, after the loss of the Colonial Military Administration during the First Battle of Shanxi and the subsequent loss of thirteen out of forty ships during the Second Battle of Shanxi led to heavy losses of matériel and personnel for the UNSC, proving to become highly critical upon the Covenant war machine. The Navy went on the offensive from 2526 to 2543 under the leadership of Preston Cole, who, while winning all battles he fought in, always phyrrically did so at the cost of half of his own forces.

During the Battle of Alpha Aurigae on 2526, 117 UNSC Navy ships were able to destroy twelve belonging to the Covenant, three of which were CAS-class assault carrier, at the cost of thirty-seven human ships and thousands of lives. The following Battle of XI Boötis saw the loss of thirty UNSC ships to the Covenant, and the Battle of the Great Bear in 2530 saw the loss of eleven destroyers by three Covenant vessels.