Sangheili-San'Shyuum War

The Sangheili-San'Shyuum War was a long and terrible conflict between the Sangheili and Reformist San'Shyuum. After eighty-six years of war, both sides reconciled their ideological differences and formed a religious alliance.
==Overview==
In the years following the unexpected and dramatic end of the , the Reformist San'Shyuum successfully expanded both their initially miniscule population and their region of control, establishing a number of minor colonies to support their search for, and investigation of, Forerunner artifacts. Over the course of more than a thousand years, the Reformists grew to over ten thousand, with a force of ships in addition to the formidable Keyship which carried the main body of San'Shyuum. With two major colonies providing provisions and materiel, San'Shyuum expeditions to ancient Forerunner worlds had become a regularity by 950 B.C.E., providing the Reformists with treasure troves of artifacts and technology which they eagerly studied and incorporated. In 938 B.C.E., analysis of navigational data scrounged from several sites indicated a world, formerly a major population and military center of the Forerunner. As befitting such a potential find, a sizable expedition of seven vessels - including the unmatched Transcendence - was dispatched in eager anticipation of what might be found. It was there the San'Shyuum encountered the Sangheili, guarding the planet against trespassers. 
The Sangheili Empire, by 938 B.C.E., had vastly grown from its humble beginnings in the Urs system: dozens of colony worlds, hundreds of spaceships, and an expanding population in the billions. Unified under a banner of militarism, expansionism, and reverence of Forerunner artifacts, the Sangheili maintained a sizable war fleet and massive armies of disciplined soldiers. In stark contrast to the San'Shyuum Reformists, the Sangheili did not condone the adaption of Forerunner technology, seeing any attempts to do so as little more than pillaging and looting of holy sites. Having come upon a world rich in Forerunner ruins, the Sangheili established a military garrison on one of its moons, refusing to land on or even name the world that they now guarded. It was this protective force that the San'Shyuum encountered over the world they had come to explore.
It was at Restless Storms that the San'Shyuum and Sangheili first encountered each other. After many hours of careful distance, San'Shyuum technicians managed to successfully run Forerunner translation systems, enabling discourse between the two species. While initial discussion was amiable and even friendly, when the topic turned to the purpose of the San'Shyuum expeditionary fleet, relations cooled immediately: the Sangheili absolutely refused to allow the expedition access to the Forerunner world, and were outraged and appalled to learn that the San'Shyuum had "named" the world. For their part, the Reformist expedition stubbornly refused to depart without first making landfall, and were frustrated by what appeared as a species dedicated to the same ideals as the long-despised Stoics. As negotiations faltered, the Reformist Council ordered their ships to disregard the Sangheili and move to land on Restless Storms. As soon as this action became clear to the Sangheili, they abruptly broke off communications and attacked with all available ships, resulting in almost immediate disaster; of the twenty warships involved, only a badly damaged cruiser survived the engagement and subsequent destruction of the lunar garrison. 
Following the one-sided engagement, the San'Shyuum proceeded to lay claim to Restless Storms, landing a large body of Reformist soldiers and scientists on the planet, and maintaining a protective force in orbit; this force was quickly bolstered with warships from other San'Shyuum worlds. The Reformists began their grand exploration of the ruins, unaware that the surviving Sangheili warship had escaped, and was proceeding with all possible speed to the nearest fleet base, Pious Fortitude. Shortly after its return, the Sangheili launched the first of several battle fleets to reclaim the world and its artifacts. The resulting battle, and the many following it, demonstrated the clear superiority of San'Shyuum technology over the raw spirit and numerical advantage of the Sangheili; despite heavy casualties, the Sangheili remained committed to retaking the planet and destroying the Reformists. 
In late 936 B.C.E., the Reformists still held Restless Storms, but both their regular fleet and available resources were greatly depleted from fighting off Sangheili assaults. The Forerunner Keyship departed Restless Storms for the San'Shyuum base colony of Tumultuous Seas, intending to load up vast supplies for the expedition, as well as conduct an inspection of the colony's defenses. It was in this brief absence that the Sangheili launched their largest offensive yet, a fleet of over six-hundred warships personally commanded by the Sangheili Arbiter, against Restless Storms. Quickly overwhelming the meager Reformist space force, the Sangheili began a major invasion of the world. The invasion came to grief, however, as severe wind and storm weather damaged assault ships about and unanticipated Reformist anti-aircraft guns shredded much of the invasion force. The sudden return of the Keyship - and all other San'Shyuum warships - precluded a second assault. The San'Shyuum flagship bombarded the assembled Sangheili ships, with the Arbiter himself and numerous senior officers the first casualties of this attack. Panicked and disorganized, the main body of the fleet fled from the onslaught and likely would have suffered greater disaster if not for the disciplined intervention of a second fleet unit; this force sacrificed itself to the last man, providing a rearguard action and saving hundreds of thousands of lives. Nevertheless, the San'Shyuum tracked the fleeing ships and successfully deduced the locations of several Sangheili worlds based on slipspace trajectories. 
The catastrophic defeat at Restless Storms precluded any subsequent Sangheili offensives for some time; the San'Shyuum exploited this fully, launching attacks on Sangheili naval installations and colonies. These attacks quickly escalated into a series of lengthy sieges of Sangheili worlds. A pattern emerged, starting in late 935 B.C.E.: San'Shyuum warships would enter the system, overwhelm Sangheili space and orbital defenses, survey the world and bombard its agricultural centers, and initiate a blockade; Sangheili forces would then attempt to first break the blockade and, failing that, resort to attempts at running the blockade to supply the starving population. These efforts were uniformly tremendously costly for the Sangheili, though they were successful at feeding those besieged. 
However, despite their continuing losses and string of defeats, the Sangheili remained utterly committed to the ultimate defeat and destruction of the San'Shyuum Reformists. Under a series of military leaders, the Sangheili Empire launched a massive naval construction program, more than rebuilding early losses and eventually outstripping continuing losses. After more than a decade of defeats and demoralizing sieges, the Sangheili undertook their Glorious Offensive in 924 B.C.E., returning to Restless Storms with a fleet of over a thousand warships. The San'Shyuum defenders called upon all available forces to Restless Storms, bringing a sudden end to their sieges. All was for naught, however, as the Sangheili relentlessly advanced against Restless Storms, compelling the San'Shyuum to finally quit the planet and withdraw completely. 
Distraught at the loss of the Forerunner world, the San'Shyuum attempted to dislodge the Sangheili from the contested system for almost two years, finally giving up in 922 B.C.E. While disabused of reclaiming Restless Storms by force, the Reformists concluded their militant opponent would require significant persuasion to abandon pursuit of the San'Shyuum and so, in early 921 B.C.E., launched a new series of raids on Sangheili settlements and bases. These raids differed from those began in 936 B.C.E. in two notable ways. First, raids were to be quick, brutal affairs, with damage preferred over outright destruction of enemy assets: if at any time a San'Shyuum commander believed his force was threatened, he or she was to immediately disengage the enemy and withdraw rapidly. Second, there were to be no sieges of Sangheili worlds. The Reformist Council concluded that the sieges of their previous offensive had spread their forces too thin. Thus, through numerous low-risk engagements the Reformists could do damage without loss to themselves.