United Nations Space Command

The United Nations Space Command is a human military, exploratory, and scientific organization. Originally the spaceborne military arm of the United Nations formed in response to widespread conflict in the Sol system in the mid-22nd century, the UNSC was incorporated into the United Earth Government upon its formation in 2170 and subsequently acted as its primary space-going arm in the subsequent centuries. Shortly after the onset of the Human-Covenant War in 2525, the UNSC was granted unprecedented emergency powers, assuming the UEG's governing functions in order to facilitate the defense of humanity from the existential threat of the Covenant.

In the postbellum years, the UNSC attempted to cede its power back to the UEG, with limited success. In the vastly changed political landscape of the post-war era, the UEG was deemed ineffectual and anachronistic, unable to adequately answer to the pressing challenges of that era such as rebuilding humanity's economic base and military power, relocating the millions of refugees displaced by the war, or establishing effective diplomatic bridges to sympathetic post-Covenant polities. These challenges prompted the creation of the Phoenix Initiative as an overarching civilian authority to oversee the reclamation process, albeit with the UNSC retaining considerable operational autonomy.

Formation
On May 1st, 2163, following fourteen months of conflict in South America, the United Nations formally votes to establish a supranational military that will take direct control of all national spacefaring assets for the duration of the crisis. Formally christened the United Nations Space Command, there was initially some resistance from non-complying countries, although thankfully most of these incidents were resolved without bloodshed. Their first formal military action was to pacify Luna of Frieden and Koslovic insurgents, whose possession of mass drivers represented an enormous threat to Earth-based cities and facilities. So complete was their assault that by the end of the year, there would be no more rebellious cells recorded on Luna for the rest of the war.

Although launched simultaneously with the Luna engagement, the UNSC would only begin the Mars Campaign in December of the same year. Later known as the first interplanetary deployment of the UNSC Marines, a series of blitzkrieg-styled attacks at the Argyre Planitia shipyards would, in spite of initial troubles thanks to a developing command structure and doctrine, prove to be an enormous success. This was a catalyst that saw the UNSC expand significantly in a short period of time, as more resources were demanded and justified to assist their efforts. They quickly sent forces all across the Sol system, efficiently destroying the sophisticated military hardware used by the Friedens and undermining the ideological strength of the Koslovics. So complete was their destruction that by the end of 2170, only seven years after the UNSC had been created, all three sides had ceased hostilities by ratifying the Callisto Treaty. This gave the UNSC total control in military matters over the colonies.

The success of the UNSC's performance eventually led to talks for a more direct reform of the United Nations itself, and it eventually blossomed in the formation of the United Earth Government. The UNSC was retained as the organization's military arm.

Post-Covenant War
Following the ceasefire of the Human-Covenant War, the UNSC returned governing powers back to the UEG and began a period of slow demobilization. However, the presence of the various Covenant remnants all throughout the Human Sphere required the UNSC to continue vast military campaigns in order to secure their former holdings. Between careful tactical planning, the introduction in the first wave of post-war spacecraft, and assistance from the Concord of Reconciliation's fleets, the UNSC were able to outmaneuver and force the majority of hostile Covenant factions out of the Human Sphere by 2558.