Towards the end of the Second Robotech War, an Invid Sensor Nebula picked up a large dispersal of spores emitted by the Invid Flower of Life. This led semi-sentient Nebula to telepathically inform the Invid Regess, who kept to herself on Optera, of Earth's whereabouts. The Regess then sent her and her entire race towards the cosmos to search for Earth and its supply of raw Protoculture. Unbeknownst to her, Earth had already been devastated by the last great Robotech war with the Robotech Masters and was being consumed by the on-going conflict with the Robotech Masters Remnant.
As the Invid made landfall, they targeted several key installations, dealing a crippling blow against the surviving United Earth Forces. This led to the decision by several key leaders of the United Earth Government to evacuate the planet, and join up with the the Robotech Expeditionary Forces in deep space.