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 Mechanoids and Daleks had first come into conflict early in the Dalek Empire's history, after the Mechanoids used a suspicion ray against the Daleks and warned them to stay out of their skies. (COMIC: Eve of War) War between the two forces was averted by the intervention of the Zerovians, who manipulated the Daleks into destroying the rogue planet Skardal, which the Daleks had set on a collision course with Mechanus, and then told the Mechanoids that the Daleks had saved them purposely. The Mechanoids called off the war, although they still considered the Daleks their enemies. (COMIC: Impasse)

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 Daleks and the Mechanoids would continue to come into conflict. The Daleks invaded the Mechanoid City again after discovering the Mechanoids had created a Mechanical Planet which had endangered Skaro. The Dalek forces were defeated, however still managed to use an atom divider to destroy the city. (COMIC: The World That Waits) Dalek forces also battled Mechanoids on Hesperus. (PROSE: War of the Daleks) When the Restoration Empire was being destroyed by an entity, the Dalek Emperor intentionally lured it to attack the Mechanoids, (WC: Planet of the Mechanoids) who proved able to defeat it. The Mechanoid Queen swore revenge on the Emperor for this. (WC: The Deadly Ally) She led an invasion of Skaro in the belief that the entity had left the Daleks few in number. In the ensuing battle, the Emperor revealed his forces were much greater than he had let the Mechanoids believe and the Dalek Prime Strategist trapped the invading Mechanoids in the entity's dimension, including the Queen. (WC: Day of Reckoning) Not long before the outbreak of the Last Great Time War, the Daleks saw to the final extermination of the Mechonoids on Magella. (PROSE: Birth of a Legend)

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) 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)

Behind the scenes
The Discontinuity Guide claimed that the Daleks, following their defeat in the 22nd century Dalek invasion of Earth, completed their time travel program, which they had began with Theodore Maxtible, before successfully invaded Earth in the late 21st century, whilst they themselves came from no later than the 23rd century, long before the Draconian Gambit. When their work was undone by the Third Doctor, the Daleks pursued the First Doctor in an attempt to neutralise his "future intervention". It is further noted that, since the Fourth Doctor inadvertently changed Dalek history so that Davros survived, this event would have occurred vastly differently if it happened at all in the new timeline.