Battle of Cassius

The Battle of Cassius took place near the planet of Cassius beyond Pluto's orbit. This happened after the First Doctor's defeat of the Dalek's plot to turn occupied Earth into a mobile warship which resulted in the occupation force being crippled. (DW: The Dalek Invasion of Earth) At the conclusion of the battle, the Dalek's solar system blockade was shattered, forcing them to leave Earth. (NA: Love and War)