When "Imperium" was published in 1977, its scenario was not connected to any other game. GDW published "Traveller" in the same year, but "Traveller" was at that point a system for running adventures in a generic science fiction setting, with no established background. However, as the company constructed the Third Imperium as the default setting for "Traveller", the situation in "Imperium" was retconned into the "Traveller" Imperium's history; it became the First Interstellar War, the first of many wars leading to the overthrow of the Vilani Grand Empire of Stars ("Ziru Sirka") by the Terran Confederation and the establishment of the Rule of Man.