


Aside from the Second Battle of Harvest in 2526, where a large force led by Vice Admiral Preston Cole barely defeated a smaller Covenant fleet, the UNSC's influence on their territories quickly dwindled in the course of their struggle. The beginning phase of the war was marked by disastrous defeats, and even more costly victories.

The planet the battlegroup was at, Harvest, was completely destroyed. The UNSC was placed on high alert. On November 1st, the UNSC stripped away the Colonial Military Administration and gave its forces to NAVCOM and UNICOM. Upon investigation from the only surviving ship, the CMA Heracles it had been discovered that humanity was not alone. In 2525 a CMA battlegroup had been decimated.

As the situation deteriorated, the UNSC created the SPARTAN-II Program. The UNSC battled them for nearly three decades. In 2492, the colony of Far Isle was razed by nuclear weapons after a massive uprising, creating a new found reason to rebel. The Callisto Incident in 2494 would begin a bloody struggle against groups of terrorists (or freedom fighters), who wanted independence. The massive difference in wealth distribution and political power, which became a hallmark of humanity by this period, led to new threats of secession from the outer ring. By this time, a ring of Outer Colonies was providing the UEG with the raw materials that made the macro-economy function with the political power remaining with the Inner colonies. The apex of human expansion would come in 2490, when more than 800 worlds were considered part of the UEG's territory, many developing into full-fledged colonies. It would become a major naval yard and training center. At about 2490, the planet of Reach would become extremely important to the UNSC. With the conflicts of Sol over, a newly powerful Unified Earth Government and UNSC began to expand into the stars. From this point, the UNSC was used by the UN in conflicts, including the Interplanetary War. In July 2164, the UNSC partook in its first battle. The UNSC was commissioned in 2163 as a military force primarily composed of Naval and Marine forces. Their ideological opponents, the Koslovics, formed a Marxist–Leninist group centered around the leadership of Vladimir Koslov around the same time. The Frieden movement was a fascist organization based on the Jovian Moons, a group that received backing from some corporations operating in the Federal Republic of Germany on Earth. UN clashes with dissident political movements, the most important of which were the "Koslovics" and the "Frieden," began the crisis that led to the formation of the UNSC.
