Interspecies Union

The Interspecies Unions is an organization formed not long after the end of the Human-Covenant War in order to keep the peace among the various species of the galaxy. It was founded by the humans and the Sangheili, and was joined by the and the Evaniptii in later years. The Union is simply a placeholder system to keep the alliance alive whilst the Covenant remnants are still active.

There is an annual congressional session lasting one human month (30 days) in which representatives of all the member species meet to rectify conflicting issues and propose new amendments in which to aid the Union. Thirty members from each represented species are chosen by that species' own jurisdiction. Each one serves a five-year term. If need be, an emergency session can be called by at least two species' Heads-of-State or by a 55% vote in session.

Post Human-Covenant War Effects (2553—2554)
When the Human-Covenant War ended on March 3, 2553, both humanity and the Covenant Loyalists were left in a desolate state. The human population had been reduced from 40.7 billion to a mere 19.4 billion, only 200 million of them being military survivors. They were left with a mere nine colonies, most of which were scattered in distant systems. Their Navy alone had become reduced to sixteen capital ships. The Unified Earth Government had become disorganized and threatened to topple, which would consequently send the human race into becoming internecine. Foreseeing this possible danger, the United Nations Space Command struggled to maintain what strength it had left and reinforced humanity against potentially opportunistic rebels emerging from hiding to attack the weakened heart of Earth's government.

The Sangheili was not as physically weakened as a species, but still faced an equally dangerous situation; the keeping of peace among their clans and families. Although their population remained steady, the predicament on Sanghelios had become chaotic. A great number of Sangheili culture had been integrated with that of the Covenant's for the past few centuries, and the sudden revelation that the Great Journey had been a lie created massive feuds between the families. As if adding insult to injury, the Separatists' alliance with humanity had caused an uproar, and was widely considered an act of dishonor. The Sangheili began to break into separate factions, some taking the side of the Separatists, some demanding to break away from the humans, and even some still believing in the Great Journey. Despite 's efforts to unite the Sangheili, several antagonistic factions were quickly formed, the most notable at the time being The Fallen.

Formation (2554—2555)
With both species realizing the toll that the war had taken on them, the Unified Earth Government quickly established contact with the Separatists and offered to form an alliance, to settle the disputes that had arisen internally in both societies and to strengthen the other against enemy factions such as the Covenant remnants. The fragile peace held for several years, enough for the UNSC to create the Reformation Act of 2555, and tentatively created the Interspecies Union with the Sangheili. The official treaty was put into effect on October 1, 2556.