Mechonoid 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) One journalist later suggested this incident to be the first skirmish of the Last Great Time War. (AUDIO: The Dalek Conquests)

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)

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)

The Daleks developed time machines of their own, however these early time machines relied on taranium creating a means of time travel that, while impressive, was highly unstable, (PROSE: The Chase) and expensive to use. (PROSE: Mission to the Unknown, The Mutation of Time)

According to human historians, the failure of the Daleks' plot with, the Gold Dalek orchestrated a new invasion of Earth using time travel. Though this invasion failed, it inspired the Black Dalek to use time travel. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) However, other accounts placed the chase to exterminate the First Doctor to be earlier in Dalek history, in the time before the Time Destructor Incident and the Great War. (PROSE: The Chase, Mission to the Unknown, The Mutation of Time, et. al)

Conflict
The Black Dalek tasked a squad of Pursuer-Daleks with hunting down the Doctor. (AUDIO: The Daleks) They located him on the planet Aridius, along with his companions Barbara Wright, Ian Chesterton and Vicki Pallister. The Doctor and Barbara learnt of the Daleks' imminent arrival via the Time-Space Visualiser which showed them the Black Dalek issuing its commands to the assassins. After a long chase, the Dalek time machine was destroyed by Ian and Barabara after they used it to return to 1965, while the Dalek squad was caught in conflict with the Mechanoids on Mechanus. (TV: The Chase)

Aftermath
The operation had consumed all of the Daleks' taranium supply and this with the destruction of the time machine, (PROSE: The Chase) severely crippled the Daleks' existing time travel research. (PROSE: Mission to the Unknown) Through strenuous, long-term efforts the Daleks eventually harvested sufficient quantities of taranium to continue to use the time machines. (PROSE: The Mutation of Time) The Daleks would later pursue the Doctor using a time machine again after he stole a supply of taranium vital for their Time Destructor superweapon. (TV: The Daleks' Master Plan)

The Dalek Conquests put forward that this incident was the "first skirmish" of the Last Great Time War between the Time Lords and the Daleks. (AUDIO: The Dalek Conquests) It was on Magella that the Daleks saw to the extermination of the Mechonoids whilst, back on Skaro, the Dalek Emperor anticipated that the Daleks were heading to war with an "ancient enemy". (PROSE: Birth of a Legend)

This incident, among others, was tactically assessed by the Time War-era Time Lords, who learnt that Dalek time capsule technology was more sophisticated than first thought; not only were they capable of precise navigational control, but they also seemed to be able to track our Gallifreyan time capsules with ease. The Time Lords lamented Ian and Barbara's destruction of the Dalek time machine, which deprived them of an opportunity to study Dalek time technology. Technical teams were dispatched to look for ways to block the temporal signature of all operational TT capsules in order to prevent the Daleks from tracking them. (PROSE: Dalek Combat Training Manual)