Ereia was a Terran supporting nation in a larger alliance of Terran aligned nations nearby the imperial border in sector 1. They'd been arming and preparing for the eventual war for years before it finally kicked off. The Terran military made sure to garrison the planet with several divisions of marines and army as well, to ensure the Nation's defenses were appropriately prepared, as well as position a small naval detachment of troop transports (in case an evacuation is necessary) as well as a small combat fleet.

For the most part, the combat would be in space, as ground forces would dig in and watch and wait. Waiting for the eventuality of a landing, and pray that the allied Navy holds so that there isn't a landing.