Pursuit of Voga

The pursuit of Voga was what ArcHivist Hegelia termed the failed attempt by CyberNomads to destroy the planet Voga by commandeering Nerva Beacon. (AUDIO: The Cyber Nomads, TV: Revenge of the Cybermen)

Dating
The Fourth Doctor, whilst visiting the Beacon later in its history but before the pursuit of Voga from his perspective, believed that it had been constructed in the late 29th century or the early 30th century. (TV: Revenge of the Cybermen) According to The Secret Lives of Monsters, the event took place in the late 29th century. (PROSE: The Secret Lives of Monsters) By one account, the event occurred in the year 2900. (PROSE: The Cyber Files)

In the CyberHive chronology, Hegelia believed that this event took place "at the end of the 25th century", the same period in which the Second Doctor confronted the CyberTelosian Controller on Telos. (AUDIO: The Cyber Nomads)

Origin
Voga was originally a full sized planet, inhabited by the Vogans, and located in the Voga system. (PROSE: Jorus and the Voganauts) During the Cyber-Wars, the Vogans started supplying the gold dust which was used in the manufacturing of glitterguns. The Cybermen, whose respiratory unit innerworkings were vulnerable to gold dust, tried to stop this by destroying the planet, but one emergency bunker, as well as some of the population, survived, which started drifting in space as a rogue planet. (PROSE: The Revenge of the Cybermen, TV: Revenge of the Cybermen)

Pursuit
Centuries following the war, Voga was captured in Jupiter's orbit. The Cybermen later discovered the planet again and attempted to destroy the remaining gold so the humans wouldn't recreate the glitterguns and destroy them before they could launch another war. The attempt was unsuccessful and the Cyberman were destroyed. (PROSE: The Revenge of the Cybermen, TV: Revenge of the Cybermen)

Aftermath
ArcHivist Hegelia hypothesised that another group of CyberNomads came across the planet Telos, reopened the Cyber-tombs of the CyberTelosians and helped to forge the new race of Cybermen, the Neomorphs, which proliferated during the 26th century. (PROSE: Killing Ground, AUDIO: The Early Cybermen)

During their attempt to destroy Earth in 2526, the Neomorph Cyber-Leader consulted the records of the Doctor. Among other incidents, he recalled the Fourth Doctor's involvement in the defeat of their attempt to destroy Voga. (TV: Earthshock)

Conflicting account
According to another account of events, the Cybermen infiltrated Nerva Beacon on a suicide mission and sought to ram the station into a gold-rich asteroid inhabited by a tribe of lost colonists. The Cybermen were thwarted aboard the Beacon by the Fourth Doctor, his companions and the Nerva crew. (AUDIO: Return of the Cybermen)

Other references
Facing the Cybermen on a Mondasian colony ship, the Twelfth Doctor recalled defeating them on Voga among other places. (TV: The Doctor Falls)

Behind the scenes

 * Return of the Cybermen is adapted from the original version of Gerry Davis' script for Revenge of the Cybermen. The most prominent change is the complete excision of Voga from the storyline, rendering the two stories nearly irreconcilable and casting confusion over which version of the "pursuit of Voga" actually took place. John Dorney, who adapted Return for Big Finish, originally included an ending scene in which the fallout of the events of Genesis of the Daleks and the Last Great Time War causes the Return timeline to become "redundant" and it is rewritten by the Revenge timeline. However, this epilogue was cut from the script.
 * Doctor Who: Cybermen states that the pursuit of Voga occurred in the late 25th century circa 2496, following the expedition to Telos in c. 2486. The remaining Nomads then combined with the Telosians to form the new Cyber-subspecies, the Neomorphs, around the year 2500.
 * The Discontinuity Guide dates the pursuit of Voga to the late 27th century. In the aftermath, the Cybermen were forced to consolidate their position on Telos, where they experimented with time travel. After acquiring an alien time vessel, the Cybermen made a failed attempt to destroy Earth and save Mondas in 1986. Then, in what was potentially their "last ditch plan", they travelled to the 26th century in an abortive attempt to change the outcome of the Cyber-Wars.