The police action that saw Joseo annex its first dominantly human world began with a corporate dispute on the human colony of New Horizons. Joseoan and Velkan merchants operating on the world had severely soured their relationships after negotiations gone foul, and the situation escalated into a corporate shooting war on neutral ground.
New Horizons' Security Force was ill-equipped to contain two private militaries tearing their world apart, and thus the colony requested military assistance from Joseo to put the paramilitaries in check. This turned out to be a huge mistake for the colony's independence, as the Joseo relief fleet chose to occupy New Horizons after ejecting the Velkans from the system. New Horizons were annexed in the same year to become part of the Federation of Joseo, to much protest from independents and Velkans.