The Forsaken — Christopher G. Nuttall

They were loyal to the Empire, but the Empire was not loyal to them ... Montezuma was an isolated world, of interest to no one, until an interstellar corporation discovered vast resources of rare materials under the surface, just waiting to be extracted and sold. The corprats legally stole the planet, crushed the native dreams of independence and brought in vast numbers of outsiders to mine the rough-hewn world, leaving poverty, pollution and deprivation on an unimaginable scale in their wake. But now the Empire has fallen and the corporation has betrayed its workers, abandoning them to fight or die on an unforgiving world …