Shanxi

Shanxi is a Systems Alliance colony located near the Shanxi Theta Mass Relay. Besides being the jumping off point for local traffic, it is notable for its involvement in the First Contact War of 2157. It was the site of several battles between the Systems Alliance and the Turian Hierarchy. Shanxi is the only human colony to have ever fallen to an alien race. The main reason for the conflict was that the Alliance allowed their explorers to open any dormant mass relays. This was a direct, if completely ignorant, violation of Council law after the Rachni Wars taught the Citadel races a lesson. The turians opened fire to prevent this from happening again.

Battle of Shanxi
After the expedition sent through the Shanxi-Theta Mass Relay was wiped out by a turian patrol fleet, a single ship survived and made it back to Shanxi. A retaliatory force was sent out by the commander at the colony, and the reinforcements destroyed the turian forces. Events escalated quickly; the turians sent more ships through the relay and captured Shanxi, but not before a message drone was sent out by the defenders, alerting the Alliance forces at Arcturus Station.

The Alliance defenders at Shanxi, besieged by the orbiting turians, were then forced to fight a guerrilla campaign on the ground. The turians, however, slowly squeezed the defenders into submission. Dropping orbiting debris, the turians would level an entire block to destroy one marine fireteam whenever they tried to get food and supplies. Eventually, with the troops starving and civilians dying every day, the garrison surrendered and the turians occupied the colony. Facing logistical problems of their own - their biology required the turians to import all of their food - they nevertheless believed they were secure, thinking the handful of ships they defeated represented the bulk of human naval forces. They were unprepared when the Second Fleet under Admiral Drescher launched a powerful counteroffensive and evicted them from Shanxi.

In response, the turians began mobilizing for full-scale war. However, after seeing the turians forced off Shanxi, the Citadel Council realised just how well-trained, equipped and adaptable the Alliance forces were, and understood that a war between the turians and the Alliance could be devastating to the galaxy. They intervened and brokered a truce.

Shanxi's Impact
Shanxi is sometimes used as an example by xenophobic political groups like Terra Firma to protest against humanity's growing interactions with alien races. When told that the turian actions at the Shanxi-Theta relay were part of a misunderstanding, equivalent to snatching a gun away from a child, Charles Saracino retorts in that case, yes, he'd take the gun away from the child, "but I wouldn't shoot them dead." The First Contact War and the Battle of Shanxi mean a lot of humans still mistrust turians. However, Shanxi also proved humanity's tenacity and military strength. It impressed the turians and the galactic community as a whole, because apart from the krogan, the turians had previously found no equals in war. The battle created a lot of interest in humans on the Citadel.

When talking to Commander Shepard about having a drink for Armistice Day, Ashley Williams confesses that her grandfather, General Williams, was the commander at Shanxi when they surrendered. No charges were ever brought but it destroyed his career. Eventually he ended up working construction out in the colonies. The stigma also meant her father's naval career never got off the ground. The prejudice of her commanders against the Williams name is likely why Ashley was never given a position in the fleet either. Ashley tells Shepard that a Williams has to be better than the best to make up for Shanxi. Apparently there are sometimes attempts by Alliance historians to exonerate her grandfather "in some official way", but nothing ever comes of them.