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 Heirarchy. Interestingly, Shanxi is the only human colony to have ever fallen to an enemy.

Battle of Shanxi
After the expedition sent through the Shanxi-Theta Mass Relay was wiped out by a Turian patrol fleet, a retaliatory force was sent out by the commander at Shanxi. The reinforcements destroyed the Turian forces. Escalating 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 the Arcturus Space 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. The Turians would level an entire block to destroy one Marine fireteam. Eventually, low on weapons and supplies, the garrison surrendered. Shanxi was eventually liberated by the Alliance fleet from Arcturus.