Command Code EBB Vortex Nine was a specific instruction set employed to deactivate the Mon Cala planetary defense services. In the course of the invasion of Mon Cala, King Lee-Char discovered that he had been tricked by Ferren Barr into instigating an outright revolt by the monarchy against the Galactic Empire; consequently, he initiated Command Code EBB Vortex Nine, directing all his military personnel to cease fighting.
Upon being given this directive, Admiral Raddus was convinced that abandoning their fight was unacceptable, and so he disregarded the command, instead instructing the Mon Cala Mercantile Fleet to detach and flee the planet.