The earth of the Rocketmen setting is controlled by the fascist Legion of Terra.
The attempted Martian invasion of Earth and the resulting Mars-Earth war left the planet damaged, in debt, and insecure. Lord Invictus rose to prominence by convincing Earth's population that the manipulative "impure" were responsible for their problems.
After Lord Invictus was elected, he quickly streamlined Earth's bloated bureaucracy with a series of public mass hangings, after which the United Earth Senate "voluntarily" disbanded. The solar system was shocked when Invictus returned from Mars with a treaty of friendship from the Martian King, Killra, and then started his conquest of the inner planets.