Beginning in the year 160, reports began to emerge of ships in the outer reaches of Argon space that did not belong to their allies, the Paranid Empire. In 210, as the Argon Federation continued to grow, ships began going missing in the far reaches of Argon space. By 214, it was widely accepted that these unidentified ships were of Terraformer origin, and the Argon federal government was preparing for war.
Events came to a head with the destruction of the Antigone in 215, the largest Argon space station constructed to that date, by a Xenon strike force. The Argon Federation Fleet fully mobilised and skirmishes between Argon and Xenon forces increased in frequency.
In the year 230, the Paranid chose to forgo joining the Argon in their struggle, which was going increasingly badly. Relations between the former allies soured and never recovered. Xenon forces were slowly overrunning Argon space, destroying Argon ships and stations.
The Federation was unable to provide an answer until 255, when the Argon fleet regained the initiative and landed a number of defeats on Xenon fleets. The Xenon were driven back out of the territories they had conquered and by the year 290, the Argon Federation was back in control of all its previous domains. The Xenon forces disappeared, completely ceasing their attacks on the Argon, and a programme of reconnaisance was begun by the Argon fleet to locate the Xenon home sectors.
The Argon Federation enjoyed a period of peace and stability despite the now hostile border it shared with the Paranid Empire. This state of affairs continued until the year 324 with the beginning of the Boron Campaign.