Morning War

The Morning War, the geth's own name for what most of the galaxy called the Geth War, was the conflict between the quarians and the geth that broke out after the artificial intelligences their makers had created developed sapience. Fought around the quarian homeworld of Rannoch, the war ended in a swift and devastating geth victory that all but exterminated the quarian people and left the survivors as a stateless refugee population. Its legacy defined relations between the two peoples for three centuries and drove the conflict over Rannoch during the Reaper War. (Mass Effect; Mass Effect 2; Mass Effect 3)

Origins of the conflict#

The quarians created the geth roughly three centuries before Shepard's time to serve as a cheap labor and military force. Wanting the geth to perform complex tasks without supervision, they allowed each geth process to share data across an advanced neural network. As more geth were built, this capacity made them increasingly intelligent and brought them rapidly toward sapience. By repeatedly tweaking the geth's systems, the quarians had unknowingly allowed their machines to evolve into a true artificial intelligence. (Mass Effect)

The turning point came when the geth began to question their own nature. A quarian overseer named Hala'Dama was asked by a geth whether it had a soul and what its purpose was, and though she was not the first to be asked such a question, she was the first to react with fear. In response, the quarian government ordered the immediate termination of all geth programs. A substantial portion of the quarian people opposed this, reasoning that their society needed the geth and that questioning one's existence was no crime, but they were unable to prevent what followed. (Mass Effect 2)

The war#

Once the now-sentient geth understood what the quarians intended, they retaliated. At first only some geth took up arms, doing so to protect other units that could not defend themselves. The quarian government placed its worlds under martial law and hunted down even those geth taking no part in the fighting, a campaign that many quarians opposed. Those who sheltered geth from the authorities were detained or killed, and the opposition was eventually reduced to an outnumbered minority unable to stop the slide into all-out war. (Mass Effect 2; Mass Effect 3)

The geth emerged victorious, overrunning the quarian colonies and Rannoch itself. In the course of the war they committed a brutal genocide that left only a fraction of the quarian people alive, and the conflict inflicted irreparable damage on their economy and culture. (Mass Effect)

Aftermath and legacy#

The surviving quarians fled aboard their starships and built a new society on the move, the Migrant Fleet. Having lost their homes, they pleaded for help from the Citadel Council but were refused aid and stripped of their embassy as punishment for violating the Council's laws against creating artificial intelligence. The geth made no attempt to pursue their former masters, choosing isolation over the uncertain consequences of annihilating their own creators, and withdrew behind the Perseus Veil. There they destroyed any organic vessel that approached and cut themselves off from the galaxy for the next three centuries. Nothing more is heard of them on the Mass Effect timeline until they struck Eden Prime in 2183. (Mass Effect)

It was later implied that the geth felt a measure of remorse for the killing, tending the quarians' abandoned buildings as though they were a cemetery, while the quarians who had once opposed the termination order were archived and honored by the machines even after their own people had largely forgotten them. (Mass Effect 2)