War of Many Banners

The War of Many Banners was a multi-faction conflict that took place across Sangheili space roughly between 995 BCE and 970 BCE. It was primarily fought between the Crimson League, Thar'shi Sphere, and Nirphal Resurgence; several other far smaller factions also participated in the war. The intensity and scale of the fighting ebbed and flowed over its duration.

The Sangheili's final large-scale civil conflict prior to the War of Beginnings and the creation of the Covenant, the War of Many Banners saw the formation of the political blocs that would, soon after, face the San'Shyuum.

Background
The War of Many Banners was set against the backdrop of what would later be broadly known as the Ages of Strife, a period of cold and hot war between several of the political blocs within the Sangheili sphere. During this time, tensions rose between the Crimson League and the Thar'shi Sphere, which became the two largest powers in the Urs system. These polities sponsored several proxy wars in the Urs system and beyond, backing opposing rebel groups and lesser clans. The Thar'shi Sphere notably backed the Nirphalite movement among the Voidborn, the spacefaring populations of the Urs system, who would several decades later come to declare the Nirphal Resurgence and challenge both major factions.

The debate over Suban
A long-running debate over claims to the moon of Suban played a large role in sparking the hostilities. Suban was originally settled centuries earlier, prior to the Skyfall, and due to the consequent dark age, records of the moon's first colonists were scarce. Suban's population became divided during the dark age, and these rifts grew even greater as the tensions of the Ages of Strife mounted. The Thar'shi Sphere and the Crimson League supported opposing sides among the moon's increasingly polarized population. The Thar'shi Sphere held that their ancestors, the Kharsim ethnic group, had settled Suban as a penal colony, a story corroborated by the folklore of the pro-Thar'shi segment of the Subanite population. However, several populations of what would become the Crimson League also had credible claims to parts of the moon, as well as a large support base among the populace.

Initial fighting at the moons of Sanghelios
Fighting between the Crimson League and Thar'shi Sphere broke around Suban proper. This fighting was initially limited to the moon itself, as neither side wanted to escalate the conflict into their other holdings or their heartlands on Sanghelios. This lasted for several years and was mostly fought by local forces. Escalation aversion eventually melted away as the local forces depleted, requiring the introduction of colonial forces into the battles.

The conflict escalated once more when the Thar'shi Sphere targeted one of the Crimson League's suppliers, the Merchants of Qikost, on the other moon of Sanghelios. Thus beginning the protracted Siege of Qikost.

The Nirphal Resurgence
In the midst of the fighting, a number of colonies and vassals from both factions attempted to secede and form a loose coalition known as the Nirphal Resurgence. This was a movement largely based around the colonies around the red dwarf Joori, whose populations still harbored grudges going back to the Joorian Reconquests. Several affiliated minor colonies within the Urs system as well as Joorian-sympathetic interstellar colonies would join the resurgent Nirphal cause, which found some supporters even on Sanghelios proper. The movement began organically but eventually was given materiel, logistical, and training assistance by the extra-Ursian Irshun League.

By the 980s BCE, the Nirphal Resurgence confronted the Crimson League in a number of places in the Urs system. Fighting between the Thar'shi and Crimson League died down briefly as both factions pivoted to confront the uprisings and attacks. Extensive campaigns in the Yervun and Lhiaron systems also took place.

Resumption of fighting
Although intermittent fighting with the Nirphal Resurgence continued, the primary two factions turned their sights back to each other once more.

Aftermath
The War of Many Banners was significant in many ways. The conflict and its accompanying arms race saw various steps toward the paradigms of technology, strategy and tactics that would dominate Sangheili doctrine at the start of the War of Beginnings.

Silver Beacon Treaty
Fighting came to an end with the signing of the Silver Beacon Treaty. The Treaty passed Suban decisively into the Crimson League's sphere of influence, and ceded two additional contested colonies to the Crimson League as well. Most of the colonies closer to Urs which joined the Nirphal Resurgence were folded back into their respective factions. The most distant of colonies were allowed independence due to resistance that couldn't be overcome. Some these independent colonies would join the Irshun League later on.

With the defeat, the Thar'shi Sphere eventually turned outward from the Urs system and focused more of their efforts on expanding their empire through colonization and conquest. This would in part lead to the colonization of Ulgethon, the site of the first battle in the War of Beginnings.