Dalek-Mechanoid War

The Dalek-Mechanoid War was a conflict between the Daleks and the Mechanoids which began with the Mechonoid Incident. (TV: The Chase, PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Beginning of the Mechanoids
The Mechanoids were originally obedient robots sent by humans to ready suitable planets for colonisation, (TV: The Chase) on behalf of IMC, (PROSE: Secrets of Time Lord Victorious) in the 24th century, 50 years before the war with the Krayt, according to one account. (AUDIO: Queen of the Mechonoids) However, Earth got caught up in interplanetary wars such as the Human-Draconian War, the Second Dalek War and the Third Dalek War which put an end to the Earth Empire's expansionist phase (PROSE: The Chase) and the colonists never arrived.

Alone on Mechanus, the Mechanoids continued to fulfill their function of keeping the colony ready for the humans if they ever arrived, and imprisoned any intruders who did not possess the colonists' original recognition code. (TV: The Chase) One account claimed they achieved sentience in this time. (PROSE: Secrets of Time Lord Victorious)

Early tensions
The Mechanoids, having grown into a fearsome interplanetary power, first clashed with the expanding Dalek Empire when they built a space station for refuelling on the route to the planet Oric. The Mechanoids used their suspicion ray on one of the Daleks there, causing it to perceive other Daleks as its enemies and kill them. The Mechanoid Interceptor which held the ray was destroyed by the Daleks, but the Dalek ship was then attacked and melted by two other Mechanoid ships. The Mechanoids then broadcasted a message to the Daleks on Skaro, warning them to avoid their territory. The Daleks instead began preparing for war with the Mechanoids. (COMIC: Eve of War)

The Zerovians, seeking to prevent war from breaking out between the Daleks and the Mechanoids, sent their robot agent, 2K, to accomplish this. The robot manipulated the Daleks into destroying the rogue planet Skardal, which they had set on a collision course with Mechanus, then told the Mechanoids that the Daleks had saved them purposely. The Mechanoids then called off the war, although they still considered the Daleks their enemies. (COMIC: Impasse)

Open hostilities
After a pursuit across time and space, a squad of Daleks followed the Doctor's TARDIS in their time machine to Mechanus. They followed the First Doctor, Ian Chesterton and Barbara Wright to the Mechanoid City and battled the Mechanoids there. As the battle raged the time travellers escaped along with Steven Taylor, an astronaut who had crash-landed on Mechanus and been taken prisoner by the Mechanoids because he did not know their code. (TV: The Chase)

The Daleks invaded the Mechanoid City on Mechanus again after discovering the Mechanoids were the creators of a Mechanical Planet which had endangered Skaro in the 27th century. The Mechanoids had been working on a Mechanical Sun to replace the destroyed Mechanical Planet. The Mechanoids came close to winning by drawing the Daleks into a successful ambush, however the Black Dalek responded by deploying the atom divider, which destroyed the city. A surviving Mechanoid swore revenge. (COMIC: The World That Waits)

The Daleks, assisted by their Movellan servants, later fought other Mechanoids, whose purpose was likewise simply to keep an abandoned colony pristine for nonexistent human masters, on Hesperus. (PROSE: War of the Daleks) By 2382, Mechanoids were no longer used by humans, and had not been for some time. (PROSE: Fear of the Dark)

Juggernauts of Lethe
Mechanoids were used to construct the human colony on Lethe, before being sealed away in a hidden chamber and abandoned for years. Davros uncovered the Mechanoid shells and combined them with organic tissue to create Juggernauts. After manipulating the Sixth Doctor to find him on Lethe, the Black Dalek ordered an invasion to capture Davros. The Juggernauts were initially successfully at repelling the Daleks, until Mel Bush changed their programming to make them attack Davros, which enabled Dalek reinforcements to destroy them. (AUDIO: The Juggernauts)

Restoration Empire
In the era of the Dalek Restoration Empire, the Mechanoids ruled their own Mechanoid Empire, led by a Mechanoid Queen. (WC: Planet of the Mechanoids)

After the Daleks had learned of the temporal fluctuations, (PROSE: The Guide to the Dark Times) caused by the Tenth Doctor poisoning the Kotturuh in the Dark Times, (PROSE: The Knight, The Fool and The Dead) they invaded the planet Islos for more information, (WC: The Archive of Islos) only to earn the ire of a hostile entity, who destroyed much of their military force. (WC: The Sentinel of the Fifth Galaxy)

Rapidly losing ground to the Entity, the Dalek Emperor travelled to Mechanus, accompanied by the Dalek Prime Strategist and a small entourage of Silver Daleks, and was met by the Queen. When the Emperor admitted that he required their aid, the Queen took him to her star chamber, leading his saucer guarded, where they reviewed the Entity's trail of destruction through the Dalek Empire. At the same time, the Strategist demanded to see a scientist and was eventually met by Mechanoid 2150, who took him to inspect the orbital defenses. The Silver Daleks became impatient and attacked the Mechanoids, who destroyed them. The Queen and Emperor observed the skirmish and she noted the lack of Dalek reinforcements, wondering if the Emperor and Strategist were now the only two Daleks left. A power drain began affecting the City, despite the Strategist and Mechanoid 2150 trying to stop it, leaving the Mechanoids defenseless. With the power completely gone, the Emperor revealed to the Queen that he had led the Entity to Mechanus. (WC: Planet of the Mechanoids) The Mechanoids defended against the Entity, during which it demanded the surrender of the Emperor. As it began breaking through, the Queen abandoned the Emperor out in the open. Together Mechanoid 2150 and the Strategist used the orbital array to send the Entity back to its original dimension. Furious at being used against the Entity, the Queen ordered the Emperor and Strategist to leave Mechanus, promising that the Mechanoids would bring an end to the Daleks. (WC: The Deadly Ally)

The Queen and 2150 led the Mechanoid attack on Skaro, but the Emperor revealed the Daleks were not as weak as the Mechanoids had been led to believe and unleashed an army of Silver Daleks. During the ensuing battle, the Queen and 2150 found the Strategist and attempted to turn him against the Emperor. He pretended to agree and they escorted him through the battle to a chamber where he and 2150 plotted to use Skaro's beam projector to send the Emperor through a portal to the Entity's dimension. The Strategist betrayed the Mechanoids at the last moment and sent their army through the portal instead. (WC: Day of Reckoning)

Extinction of the Mechanoids
The Mechanoids' last stronghold was on Magella. The Daleks, at a time when their Emperor anticipated a coming conflict with another enemy, attacked and destroyed all the Mechanoids, making them extinct. This effort was led by the Dalek Commander of the Seventh Incursion Squad, who would be named leader of the Cult of Skaro, known as Dalek Sec, by the Emperor in light of the success. (PROSE: Birth of a Legend)

Legacy
On Red Rocket Rising, the Eighth Doctor mockingly asked the Dalek Supreme if the Daleks were currently fighting the Mechanoids, amongst other enemies. (AUDIO: Blood of the Daleks)

During the 41st century, Mechanoid shells were recovered from worlds ravaged by the Daleks and brought to Station 7. At some point, a New Dalek Paradigm force attacked the station while searching for "the Abomination", and the Mechanoid shells were destroyed along with the station. (COMIC: The Only Good Dalek)

During the Time War, the Time Lords cited the Mechanoids as an effective example of anti-Dalek weaponry, as evidenced in the Mechonoid Incident. The Dalek Combat Training Manual noted that the machines, should they be reprogammed, could provide an excellent line of defense against Dalek attacks. (PROSE: Dalek Combat Training Manual)

Human historians in the post-Time War universe, following the Siege of Trenzalore, understood that "the war between the Daleks and the Mechanoids" began with the Mechonoid Incident and lasted for centuries before the Daleks prevailed. The Daleks' new conquests had turned their advance towards the Outer Galaxies in the half a millennium leading up to their attempt to invade Mutter's Spiral in the year 4000. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Behind the scenes

 * A destroyed Mechanoid is part of the "junkyard stretching across eternity" left over from the Time War in NOTVALID: The Ninth Doctor vs the Cybermen.