Third Dalek War

The Third Dalek War was a war fought between the empires of Earth and the Daleks, some time after the Human-Draconian War and the Second Dalek War which both took place during the 26th century. There was a tremendous number of human casualties and added to the losses of the previous conflicts, this brought the Earth Empire's vast population growth to and end that thus concluded their expansionist phase. Planets such as Mechanus were left uncolonised and the Mechonoids, Earth's servant robots, completely faded from memory though the robots continued to wait for the human colonists, but they never arrived. (PROSE: The Chase)

By the time of the Third Dalek War, the location of the Lucifer star system was of paramount strategic importance, but neither the Daleks nor the Earth Alliance could go anywhere near it as there was a total exclusion zone, a kind of force field generated by the black holes worshipped by the Angels. IMC wanted Ace to time travel to around 2154 to gather intelligence about it. (PROSE: Lucifer Rising)

EarthDoom XV was a holo-vid series that presented a highly fictionalised account of the Third Dalek War. Chris Cwej watched it as a child. Despite its low production values, it terrified him. (PROSE: Sky Pirates!)

The final action of the war was the Exxilon Gambit. (PROSE: The Secret Lives of Monsters)

Aftermath
The events of the war were recorded in the book, A History of the Dalek Wars, by Hagan Garsonomous. (PROSE: The Secret Lives of Monsters)

Four Dalek survivors remained on Exxilon. (TV: Death to the Daleks)

Behind the scenes

 * The first in-universe mention of the Third Dalek War is in John Peel's 1989 novelisation of The Chase. Future stories in the Virgin New Adventures, Lucifer Rising and Sky Pirates!, do contain references to the Third Dalek War. However, more novels tend to concern themselves with the Second Dalek War, such as Love and War, Return of the Living Dad, Deceit, Abslom Daak... Dalek Killer and Prisoner of the Daleks.
 * In the televised version of The Chase from 1965, Steven merely makes reference to "interplanetary wars". John Peel replaced this with specific examples when novelising the serial, since the mythos was much larger.
 * A Dalek Wars source from Doctor Who: Battles in Time #55 gives an account of the final battle of the Third Dalek War, although it is fought by the Second Great and Bountiful Human Empire rather than the Earth Empire, which would mean it wouldn't fit into the same time period as the Human-Draconian War. After being all but defeated by the humans, the Supreme Dalek sent the remaining forces to attack the planet JT227, a planet rich with the element Promethium 62 which the humans were using to break Dalek forcefields. However, the humans' Spindroids mining the element fought back and proved resistant to Dalek fire and the Daleks were pushed back from human space.