Reaper Incursion

The Reaper Incursion was a major intergalactic conflict pitting the civilizations of the Milky Way galaxy in a crucial struggle against the Reaper armada. The war was instigated by the Reapers, a semi-organic race of dreadnoughts bent on continuing their ancient cycle of extinction and purging all sentient life from the galaxy. What followed was a long-running and costly war that ultimately led to the deaths of billions and the destruction of entire worlds.

The Vanguard
The countdown to this bloody conflict began in 2162 when a survey team employed by discovered an ancient artifact in the Perseus Veil -- a Reaper named Sovereign. Edan hired an expert named to secretly research this unprecedented find but didn't realize the mind-warping affects that Reapers possessed. As a result to his exposure to Sovereign, Dr. Qian had gradually become indoctrinated to the point of obsession over the research. Both Qian and Had'dah would later be tracked down to by  who subsequently killed both and took their research, hoping to find what he believed to be a weapon capable of humbling humanity once and for all.

Though Edan's survey team found it and Dr. Qian that studied it, Saren would be the one to reactivate Sovereign from its dormant state. After learning of its intent, Saren attempted to save the galaxy by proving the usefulness of organics to the Reapers; an act that proved to be the first attempt at avoiding the inevitable war. Sovereign gladly aligned itself with Sovereign, having no intentions of sparing Saren or any beings in the galaxy, and began making preparations in bringing about the Reaper invasion. For many years, Sovereign conducted many of his operations through Saren, progressing in its plan while going largely unnoticed, but it later became bold enough to launch its first full-scale assault on organics.

Shepard's Intervention
In 2183, Sovereign led an army of in a raid on  in an attempt at obtaining the unearthed Prothean beacon there and knowledge on the whereabouts of the. This attack, which was thought to be launched solely by the geth by the galactic majority, later proved to be a fatal misstep for Sovereign as it led to the intervention of Miguel Shepard -- the first human spectre. Shepard initially believed that the attack was an act of war initiated by Saren, but after launching a galaxy-wide investigation he learned about Sovereign, the Cycle of Extinction, and their inevitable arrival. With little to no help from the, Shepard and the crew of the became all that stood between Reapers and the galaxy.

Shepard eventually brought about the end of Sovereign during its attack on the Citadel, an engagement that would be known as the and later, the first battle of the Reaper Incursion. In spite of both Saren and Sovereign being felled, Shepard knew that the invasion had only been stalled temporarily and that plans still needed to be made to combat the Reaper menace. Eitherway, he managed to deny the Reapers of an invaluable component to their cycle by keeping the heart of galactic civilization as well as their leadership intact. The battle was not without its setbacks, however, as a large portion of the Citadel Fleet was obliterated and the Council still denied the existence of the Reapers, leading Shepard to resort to desperate measures.