Mechanoid Incident
The Mechonoid Incident was the Time Lord designation for the event in which the Daleks pursued the First Doctor and his companions through time. (TV: The Chase, PROSE: Dalek Combat Training Manual)
The Black Dalek ordered a squad of Daleks to hunt down the First Doctor using a time machine in revenge for his role in the liberation of Earth in the 22nd century. The ensuing pursuit across time encompassed numerous planets and time periods, culminating on Mechanus where the Daleks engaged the native Mechanoids in battle. (TV: The Chase)
History
Prelude
On his early travels, the First Doctor became a recurring enemy of the Daleks, (TV: The Daleks, AUDIO: Return to Skaro) notably being instrumental in the overthrow of their occupation of Earth in the 22nd century. (TV: The Dalek Invasion of Earth)