Oasis City was originally constructed by colonists during the US Empire's early colonization period, during the colonization of New Madrid. Using massive Terraforming Towers, the colonists brought life to the barren planet. A Terraforming Tower stands tall in the city to this day, continuing its work.
The city saw conflict during the Outer Rim War, being captured by the ruthless Arm of Orion. Fortunately, the city was liberated by USIF troops, and the battle at Oasis City proved instrumental in driving Arm troops off the planet.