War for Kanassa
Main article: Dragon Ball Z: Bardock - The Father of Goku
For some time, the Frieza Force had been attempting to conquer Planet Kanassa. It is revealed that the planet holds some form of secret energy that allows its inhabitants to develop psychic abilities, as Frieza apparently wanted to take hold of the planet in order to harness said energy. However, despite numerous attempts, even Frieza's elite squadrons were unsuccessful in conquering the planet. Somehow, the Saiyan Bardock and his team found their way to Kanassa and joined in on the fight as a way to show Frieza that they deserved more recognition.
Bardock and his team consisting of Tora, Fasha, Shugesh and Borgos waged battle against the Kanassans for a few days, waiting until the full moon finally arose to launch their final assault. The full moon caused the Saiyan transformation into Great Apes, which gave them the power to easily eradicate the population of Kanassa within one night. After the battle had finished, only one Kanassan by the name of Toolo survived. With this, he attacks Bardock and transfers his psychic abilities over to the Saiyan warrior, thus sparking a chain of events that would later lead to the Saiyan race's end. Bardock then slaughters Toolo, thus finally killing off all of the population, allowing Frieza to take control over the planet.
A short time later, Zarbon, Frieza's right-hand man, informs Frieza that a band of low-class Saiyans had taken over Kanassa in just a few days. Dodoria, another of Frieza's main henchmen, states that the job to take Kanassa had been in the pool for months, and that not even Frieza's elite squadrons could take Kanassa so easily. This is the first time Frieza is literally amazed as to the growing power of the Saiyans. Frieza, Zarbon, and Dodoria contemplate the fate of the Saiyans due to the growing power of the species and decide to take action in order to avoid further repercussions, as the Saiyans might pose a great threat to them in the future.