Thal-Dalek War

The Thal-Dalek war was a conflict between the Thals and the Daleks which lasted over a long period of time, though we have scant detail of most of the events that happened over the course of the war.

Duration
Some time after the Thousand Year War, the planet Skaro had been changed into a nuclear wasteland with the principal features being the petrified forest, in which the Thals lived, and the city of the Daleks. The Doctor and his companions, Ian Chesterton, Barbara Wright and Susan Foreman, visited Skaro at this time and led some of the Thals to attack the Daleks in their city, disabling the power generator and depriving the Daleks of the static electricity they needed to move about the city. (DW: The Daleks)

The Daleks did survive. Accounts of the first conflict and of the part the travelers played in it passed into Thal legend.

Circa 2540, the Daleks had built a base on the planet Spiridon, and planned to launch an army of ten thousand Daleks, which they had hoped to render invisible by study of the native Spiridon humanoids, across the galaxy. The Doctor helped a taskforce of Thals, who by this time had interstellar spaceflight to defeat the Daleks, this time using the ice core of the planet to freeze the Dalek army. (DW: Planet of the Daleks)