The Rustfire is not only the first in the chain of Union ships, but also represents the origin of the Union itself. It is based on 'Mad' Max Shepard’s own first ship, a refitted Rustclaw.
To make this vessel more effective in his smuggling runs, he replaced the useless mining equipment with a simple, yet effective construction to mount an additional gun and missile. With more armour added, the ship became an efficient blockade runner. It is not a high class fighter, but at several occasions patrol ships realized too late that this ship has more than the expected firepower of a Rustclaw. Shepard himself claimed he had once even shot down a Hawk-class fighter with his Rustfire, but this is most likely not true.