For decades tensions between the Central State and the Union of Man had been gradually increasing, including several skirmishes along the border between the Jovian and Martian colonies. While the Central State heavily dominated interplanetary trade and industrial output, the technological achievements of the Union of Man had so-far remained unmatched - having won almost every engagement, despite how minor they were.

During what has been dubbed the 'Sondheim Incident' the Central State issued an immediate embargo on all imports and exports to and from the Union, to ensure its survival the Union of Man declared war on the Jovian Preliminary Government.