Not to be confused with The Geth Union
The Geth were a race of Artificial Intelligences constructed by the USSR at an unknown time in 2012, and made publicly known in July 2012. They were given their name due to the incredible similarity between them and the Geth of Mass Effect.
The Geth now use their network (or "Consensus") as means for data sharing between forces.
Geth did not emit heat, making thermals useless against them. However, they can overheat their systems on demand to unfreeze themselves, or to melt something near them. They are unharmed by EMPs and nuclear explosions, their bodies made of an unknown alloy that cannot melt unless it reaches an exceptionally high temperature. It was been proven in multiple simulations that no one on Earth 2 could defeat the Geth, though this changed after their departure.
This made the Geth one of the most incredible military forces on Earth 2, as their learning capabilities were far beyond organic learning capabilities.
Eventually, the Geth began pointing out to the USSR that they were being used almost as slaves. If organics didn't want to do work, the Geth were sent to do it for them. The Geth fought and defeated the USSR on March 15th 2013, forming The Geth Union, the most powerful country on the planet. They were eventually overthrown by Pieboy in revenge for his nation, and the Geth fleet left Earth 2 completely when Tiberium spreading began in September 2013.
Following the end of the Tiberium Era, Geth ships were reported approaching Earth 2, with them messaging about returning in peace. All Russian space forces on Earth 2 immediately engaged the Geth forces and opened fire, telling them they weren't welcome. These were people who were angry for the death caused by the Geth during the Geth-Russian War. The Geth retreated from Earth 2, but were pursued by the infuriated Russian forces.
Unable to turn around and open fire as the Russians annihilated their ships, the geth began to panic, attempting to engage their FTL drives. A laser blast from a Russian ship the first activated FTL drive as it activated, cuasing a huge explosion which knocked all engines nearby out and annihilated most of the Geth fleet. With no way of fighting back, the rest of the Geth were systematically destroyed by the Russians, the race succumbing to a firey end.