Treaty of 2552

"I promise this to every man, woman and child on Earth and in its colonies. While we will continue to strive for a peaceful coexistence with other species, humanity will never again allow itself to be the victim of aggression. This is the moment we start to reclaim our rightful place in the universe."

- President Ruth Charet's inaugural speech

The Treaty of 2552, also known as the Ceasefire of 2552, is an agreement of peace between the Unified Earth Government and the Fleet of Retribution—or more generally, most of humanity and Sangheili—that brought an end to the Human-Covenant War. Although the war officially ended on March 3, 2553, the fighting between humanity and the Covenant ended on December 11, 2552. The treaty's title refers to the peace agreement and alliance developed between the Sangheili and the United Nations Space Command in 2552, although the Treaty of 2552 was formally ratified in February 2553 with the Swords of Sanghelios. The era following the war is referred to as the Treaty period by some individuals.

The Swords of Sanghelios are the only known ex-Covenant group to maintain diplomatic relations with the Unified Earth Government (UEG); for example, no formal treaties existed between the UEG and Kig-Yar governments as of March 2553. However, the majority of the former Covenant species at large are no longer aggressive toward humanity, and Kig-Yar, for example, continue to trade with humans and Sangheili. The UEG and the Swords of Sanghelios attempted to form a peace treaty with a Jiralhanae clan led by Chieftain Lydus on Ealen IV in March of 2558, but these peace talks were disrupted by a mercenary group.

Terms
The Treaty of 2552 declared the cessation of hostilities between humanity and the Sangheili. The peace treaty forbids any party of the agreement from landing on the remains of Installation 04 and a 500 light-second exclusion zone was established around Threshold, with both Sangheili and human warships patrolling the region. However, Sangheili and UNSC forces continue to monitor Installation 07 and worked together to prevent potential Flood outbreaks, while the UNSC has established research facilities orbiting Installations 03 and 05. Regions of space held cooperatively between the Unified Earth Government and the Swords of Sanghelios, called Joint Occupation Zones, were established, as were research and military pacts formed between the two governments. Terrorist groups and splinter cells continued to directly violate the treaty's terms by attacking the parties of the treaty.

History
The Human-Covenant War lasted just over twenty-eight years. The war, primarily occurring in the Orion Arm of the Milky Way galaxy, led to the destruction of a majority of the Unified Earth Government's colonies, over 23 billion human causalities, and the dissolution of the massive Covenant empire. In the final year of the war, the remaining Hierarchs of the Covenant replaced the Sangheili with the Jiralhanae in an effort to gain an unquestioning military. This led to the Great Schism and the entire Sangheili species was ejected from the Covenant. The most organized group of Sangheili was led by Arbiter Thel 'Vadam and Special Operations Commander Rtas 'Vadum. Recognizing that the Sangheili were too disorganized to properly seek revenge against the Covenant, 'Vadam and 'Vadum reluctantly agreed to work together with members of the UEG's United Nations Space Command to defeat the Covenant. Initially, however, there was no truce between humanity and the Sangheili species at large; at the onset of the Great Schism, the Sangheili on High Charity continued to engage both Covenant and UNSC forces in the midst of the confusion, additionally Xytan 'Jar Wattinree's forces at Joyous Exultation remained hostile to both Covenant and UNSC as well. Ultimately, the UNSC and the Sangheili Fleet of Retribution were able to work together to dissolve the Covenant at Installation 00 and stop a potential galactic Flood outbreak. With the war over, relative peace was finally seen by humanity for the first time in years. Fleet Admiral Lord Terrence Hood was invited to Sanghelios by the Arbiter to formalize the peace treaty between the UEG and the newly established Swords of Sanghelios, ratifying the Treaty of 2552. The official treaty was signed and ratified by Hood and 'Vadam. On March 3, 2553, 'Vadam and 'Vadum were invited to Earth for the Voi Memorial, a tribute to the soldiers that lost their lives in the war.

After the signing of the treaty, the Arbiter traveled across Sanghelios and visited each state to make his case for permanent peace with humanity throughout early 2553. He reminded the Sangheili that if anyone disagreed with him, they could attempt an assassination as per Sangheili tradition. In Mdama, although many keep elders did not agree with 'Vadam's ideals and beliefs, Kaidon Levu 'Mdama pledged that his state would side with him for the good of the Sangheili.

Later, after the UNSC helped 'Vadam fend off the attack by the Servants of the Abiding Truth, the Arbiter was in talks to visit the. The Swords of Sanghelios also participated in simulation exercises with SPARTAN-IV forces as part of the ANVIL initiative. The UNSC also provided security during peace talks between the Arbiter's faction and Lydus' clan in 2558.

On October 27, 2558 Spartan-IV Fireteam Osiris, led by Jameson Locke, arrived at Sanghelios in their search for John-117 and the rest of Blue Team. Osiris assisted the Swords of Sanghelios in battle against Jul 'Mdama's Covenant while they laid siege on the Elder Council Chamber. After Jul 'Mdama's Covenant was pushed back, Fireteam Osiris supported the Swords of Sanghelios in their attack on the Covenant's final stronghold in Sunaion.

Reactions and controversies
Although the reaction to the treaty was mainly positive on both sides, many humans and Sangheili were still opposed to peace between the species. Despite harboring dislike for the species, most humans accepted the treaty and saw it as a step in the right direction. However, groups such as Sapien Sunrise, an extremist xenophobic organization, were heavily opposed to peace with the Sangheili. Based in the Outer Colonies, Sapien Sunrise had access to military hardware, and in 2558 used it to infiltrate a peace delegation on Biko, planning to assassinate the human ambassadors and blame it on the Sangheili. However, their plan failed when Spartan John-117 killed the terrorists and rescued most of the delegation.

In 2552, just days after the treaty was finalized, the treaty was violated by SPARTAN-II Gray Team who used a NOVA bomb to destroy the Sangheili planet of Glyke during Operation: SUNSPEAR, killing billions and committing genocide after the treaty was in effect. However, Gray Team was unaware of this fact, having only been aware that Earth was under attack the last that they knew. When Gray Team resurfaced in 2558 following the Battle of Carrow, Thel 'Vadam chose to formally pardon them for their actions.

The treaty was violated by the Office of Naval Intelligence in 2553 when the covert intelligence unit Kilo-Five was tasked with inciting insurrection between various Sangheili factions to keep the Sangheili from gaining strength, with ONI directly violating the treaty in March 2553, when the, captained by Serin Osman, destroyed a number of 'Vadam's ships by posing as a Kig-Yar pirate ship.

In 2556, after the Terrorist attack on Sedra City by a Sangheili terrorist, information from a smuggler named Axl led Commander Jameson Locke's unit to discover Alpha Shard where a new element created from the destruction of Installation 04 was used to create a bioweapon fatal only to humans. As visiting Alpha Shard was a violation of the treaty, the joint mission between ONI and the Sedran Colonial Guard was also meant to gather proof of the Covenant violating the treaty by capturing the smugglers. The team failed to bring back any living smugglers and most were killed, but the deposits on Alpha Shard were destroyed by Colonel Randall Aiken using a HAVOK tactical nuclear weapon, preventing any more of the element from being mined and turned into a bioweapon.

Although Thel 'Vadam gained a strong following through his cooperation with humanity, many Sangheili believed he betrayed his people. As with humanity, Sangheili extremist organizations began to form. One such group was led by Otar 'Bemet, who in 2555, conspired to kill the Arbiter with weapons they were planning to steal from a manufacturing facility in the Qish'tani region of Tolvuus, Sanghelios. The plan failed, however, when one of the Arbiters soldiers, Usze 'Taham, killed the conspirators. Discontent over the treaty led to the rise of many belligerent Covenant remnants, particularly the group led by Jul 'Mdama who believed humanity was the most urgent threat the Sangheili faced, particularly after discovering ONI supplying the Servants of the Abiding Truth and escaping human capture.

List of appearances

 * Halo: Glasslands
 * Halo: The Thursday War
 * Halo 4
 * Halo: Spartan Assault
 * Halo: Mortal Dictata
 * Halo: Nightfall
 * Halo: Hunters in the Dark