Spiridon campaign

The Spiridon campaign, (PROSE: Remembrance of the Daleks) also recorded as the Spiridon incursion in the Dalek Survival Guide (PROSE: Dalek Survival Guide) and known as the Spiridon Incident to the Time Lords, (PROSE: Dalek Combat Training Manual) was a preliminary stage of the Second Dalek War. Beginning as an operation by the Daleks to awaken an army in hibernation ahead of an attempted conquest of Mutter's Spiral, it grew into something of a military campaign when the Dalek base on Spiridon was infiltrated by opposing forces. Among them were the Thals, continuing their own struggle against the Daleks, and the Third Doctor, who had followed the Daleks to the planet with the assistance of the Time Lords. (PROSE: Planet of the Daleks)

Preparations for galactic invasion
In the wake of the Human-Draconian War of 2520, the Daleks planned Operation Divide and Conquer, (AUDIO: The Dalek Conquests) a mass deception tactic intended to exploit the volatile galactic politics to spark a second war between the Earth Empire and the Draconian Empire. With the aid of, the plan was put into action. (TV: Frontier in Space) By some accounts, this plot marked the first new attempt to enslave Earth's galaxy since the failure of the 2150s Dalek invasion of Earth. (PROSE: The History of the Daleks, Dalek Combat Training Manual)

As part of the preparations, the Daleks quietly occupied the planet Spiridon, the seat of the native Spiridons' civilisation that had since fallen into ruin. Though the Spiridons had evolved to master a natural invisibility to protect themselves from their world's hostile wildlife, it did not save them from the Daleks, who saturated the jungles with killer rays. Unable to hide or resist, the Spiridons surrendered and submitting to co-operating with the Daleks, though a few tried to rebel against the occupation. The slaves were kept visible with purple fur robes. (PROSE: Doctor Who and the Planet of the Daleks)

The Daleks repurposed an old Spiridon temple for use as the entrance to a subterranean command centre and sent an army of 10,000 Daleks into underground hibernation until the time came to begin the invasion of the galaxy, starting with the Galactic Core. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

In addition, this army was to be treated with invisibility techniques adapted from those naturally practiced by the Spiridons. The initial experiments were not fully successful and more work was needed. While the Daleks discovered an anti-reflecting light wave, it required a lot of energy to sustain. Some of the Daleks either reverted back to visibility after a short time or succumbed to light wave sickness.

The Third Doctor later assessed that Operation Divide and Conquer was intended to make the Daleks' galactic conquest easier, but the size of the army on Spiridon indicated that the Daleks intended to invade regardless of whether or not the deception was successful. (TV: Planet of the Daleks) The Time Lords who scrutinised Dalek history during the Time War, however, believed that this invasion had been "aborted". (PROSE: Dalek Combat Training Manual)

Thal expedition
The Thals, by this time, had attacked and reclaimed Skaro from the Daleks. (PROSE: The History of the Daleks)

By intercepting coded Dalek transmissions, the Thals discovered that the Daleks were operating on Spiridon and a small expedition led by Miro travelled to the planet to deal with them. Due to incomplete intelligence and Dalek secrecy, the Thals believed the Daleks numbered no more than twelve, having occupied Spiridon as a scientific group primarily to study invisibility techniques. Miro's expedition was formed of him and six other Thals who volunteered for the mission, armed with various weapons and explosives, but upon arrival on Spiridon, the ship crashed, communications failed and Miro was killed, though the site was still useful to the Thals as a base. (TV: Planet of the Daleks)

Although Vaber was Miro's second-in-command, the expedition doctor, Taron, technically outranked him. (PROSE: Doctor Who and the Planet of the Daleks) As next in seniority, Taron took command and adopted a highly-cautious approach. Early on, Taron, Vaber and Codal were separated from their other three teammates, who were presumed dead and never found. Vaber opined that Taron had made "a fine mess" of the expedition. Taron had formed a plan for attacking the Daleks but the losses his party suffered forced him to abandon it and he completely forbid taking unjustified risks.

After the expedition's arrival, the other Thals broke more of the Dalek code and realised their intelligence failures. The code revealed that a force of 10,000 Daleks was hidden somewhere on the planet. Because of the communications failure, Latep, Rebec and Marat flew to Spiridon to warn and reinforce the remnants of the original party. (TV: Planet of the Daleks)

The Doctor's appeal to the Time Lords
Concurrently with the early Thal expedition, the Third Doctor and Jo Grant had uncovered the truth behind Operation Divide and Conquer. The Doctor took part in a joint expedition with Earth and Draconian government officials to the Ogrons' homeworld, where the Daleks captured them. Leaving the prisoners in the Master's custody, the Daleks departed to "return to our base and prepare the army of the Daleks." Breaking out of captivity, General John Williams and the Prince of Draconia fled home to warn their people about the Dalek conspiracy at the Doctor's urging. He and Jo made it back to the TARDIS and sent an urgent message to the Time Lords, (TV: Frontier in Space) asking for their aid in following the Dalek ship off the planet. The Time Lords obliged, directing the TARDIS to Spiridon. (TV: Planet of the Daleks)

By one version of events, the Doctor was injured escaping the Master's captivity after he was hit by a stray gunshot. (TV: Frontier in Space, Planet of the Daleks) Another version holds that the Doctor went unscathed and nearly apprehended the Master, but he was forced to let him go free in order to chase down the Daleks. (PROSE: Doctor Who and the Space War) The Doctor was subsequently injured in a Dalek ambush during the pursuit before the TARDIS landed on Spiridon. (PROSE: Doctor Who and the Planet of the Daleks)

First Thal attack
The Doctor's injuries left him unconscious and confined to the TARDIS. Recording a log of events, Jo went off alone in search of help and encountered Taron's remaining Thals in their downed ship. The Thals agreed to help the Doctor but Jo was then infected with fungal spores from a sponge-plant and taken into hiding by Wester, one of the Spiridons resisting the Daleks. The Doctor, meanwhile, recovered as he was located by Taron's party and they filled each other in on their respective missions against the Daleks. The initial link-up was brief, however; the Doctor was captured by the Daleks as they found and destroyed the Thal ship. The Doctor retrieved the lost TARDIS log but was unaware Jo was no longer onboard the ship. Codal too was captured by Spiridon slaves.

Taron and Vaber hid their explosives away in a cache. Vaber nearly mutinied but Taron talked him down. Thereafter, they were joined by their reinforcements, who crashed on the planet but survived, and warned the others of the true strength of the Daleks. They infiltrated the Dalek base through the ventilation systems, hoping to cause a cave-in with some of the explosives, but the charges failed. Simultaneously, Jo entered the city with Wester's help by hiding herself in one of the baskets being moved by the slaves, and managed to eavesdrop on the Dalek control centre. The Doctor and Codal also escaped their cell when the Doctor modified the TARDIS log to interfere with the control systems of a Dalek on guard.

Detecting the prison break, the Daleks made sure to lure the escapees to level zero. There, the Doctor and Codal linked up with the rest of the Thals, though Marat was killed helping the others to escape. The Doctor caught a glimpse of the army before he and his allies ascended a ventilation shaft to the surface ahead of a Dalek patrol and reunited with Jo. (TV: Planet of the Daleks)

Second Thal attack
Displeased with the progress, (PROSE: Doctor Who and the Planet of the Daleks) Dalek Supreme Command decreed that the Daleks must prepare a bacteriological virus to destroy all living tissue on Spiridon. Daleks and Spiridon slave workers would be given immunity while the virus killed any intruders if they were not captured before its release. With fugitive at large, the Dalek Section Leader issued a state of emergency and suspended all normal operations.

The Thals considered their attack a failure, with Vaber running off in defiance of Taron, only to be killed by the Daleks. Yet the Doctor urged a second attack intended to freeze the army with molten ice from redirected icecano eruptions, (TV: Planet of the Daleks) based on useful information learned from the first attack. (PROSE: Doctor Who and the Planet of the Daleks)

Dalek patrols moved to intercept the Thals in the Plain of Stones but they were ambushed and deactivated in a molten ice pool. The Thals then re-entered the city using Spiridon robes and a Dalek casing as disguises. While they launched a two-pronged attack, Wester launched a third, sacrificing himself to release the virus prematurely. The Daleks had not yet completed the immunisation process and the Dalek Scientists had to seal themselves inside the laboratory. (TV: Planet of the Daleks)

"Attack force is totally immobilised"
During the ongoing hunt for the Thal agents, the Dalek Supreme arrived on Spiridon to take personal command of the operation. The Dalek was the head of the Supreme Council and second-in-command to the Dalek Emperor. (PROSE: Doctor Who and the Planet of the Daleks) Supreme Command identified the Doctor and ordered him to be captured for interrogation, but the Dalek Supreme was infuriated by the Section Leader's persistent failure and exterminated him.

Beneath the control centre, the Thals detonated a bomb over the catwalk in the cavern holding the army as it began to stir. Upon the next eruption of an icecano, the cavern was flooded with molten ice, ensuring the army remained inert. (TV: Planet of the Daleks) All remaining Daleks of the initial expeditionary force were dispatched to capture the invaders, and were either caught in the explosion or trapped by the ice. This left the Dalek Supreme and his two aides as the only three Daleks still free in the base. (PROSE: Doctor Who and the Planet of the Daleks)

The Doctor and the Thals made their escape as molten ice flooded the rest of the base. The Dalek Supreme ordered that the facility be abandoned and all instruments set to self-destruct. Taron and his party made their back to Skaro by hijacking the Dalek Supreme's ship. Stranded on Spiridon, the Dalek Supreme called for a rescue ship to be sent by Supreme Command and decreed that preparations would begin immediately to free the buried army. He declared, "We have been delayed, not defeated. The Daleks are never defeated!" (TV: Planet of the Daleks) Even so, the Dalek Supreme acknowledged that the day had been one of "total catastrophe". Although he appealed for a rescue ship, (PROSE: Doctor Who and the Planet of the Daleks) historians later claimed that the Dalek Supreme was lost on Spiridon, in a blow to the Supreme Council. The Spiridons subsequently reclaimed their planet. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Aftermath and legacy
The Doctor informed the Thals that upon their return home, they would be celebrated as heroes. He warned them not to romanticise the tale by making war sound like a fun and exciting game, reminding them to talk about the losses and fear, lest the Thals come to relish the idea of war (TV: Planet of the Daleks) like their ancestors had. (TV: Genesis of the Daleks)

Rebec was later interrogated by the Celestial Intervention Agency as they researched the Daleks; her notes on how a humanoid may drive a Dalek casing from the inside were added to Ian Chesterton's, which she was given the chance to read before writing down her own testimony. (PROSE: The Dalek Problem)

From the Doctor's perspective, after leaving Spiridon, he and Jo ended up in another Dalek War, requiring them to halt the awakening of another Dalek army. (AUDIO: The Conquest of Far) Shortly after, they arrived on Catastrophea (Kastopheria), and became embroiled in another human-Draconian relations crisis prior to the 2520 war. (PROSE: Catastrophea)

The failure of both Operation Divide and Conquer and the Spiridon campaign meant that the Daleks did not enter the Second Dalek War on their own terms. Nevertheless, the First Dalek Incursion, at the start of the war, was a ferocious event, with numerous planets destroyed. The war lasted "over forty years" beyond the Incursion and Earth Central eventually became desperate enough to hire bounty hunters and criminals, although the Daleks were ultimately defeated. Towards the end of the war, they had upgraded the casings of their military forces to a bronze "protective armour", (PROSE: Prisoner of the Daleks) which first applied to one of the successor of the lost Dalek Supreme. (AUDIO: Out of Time)

Shortly after the war ended, (PROSE: The Chase, Deceit) the Daleks made further ventures into biological warfare. During the Third Dalek War, they launched plague missiles at the Outer Worlds of the Earth Empire, causing a deadly outbreak of space plague which led to the Exxilon Gambit, (PROSE: The Secret Lives of Monsters) a dash by humanity and the Daleks to acquire a rare mineral, parrinium, which acted a cure. (TV: Death to the Daleks) As was noted by Njeri Ngugi, the historian who authored The Children of Davros, Dalek use of biological weapons such as in the Spiridon campaign bred a dangerous complacency. Future Daleks failed to consider their own vulnerability to biological attack, which presented the Movellans with the opportunity to devastate the Dalek Empire with the Movellan virus at the end of the Dalek-Movellan War. (PROSE: Remembrance of the Daleks)

The Dalek army on Spiridon was never recovered for the duration of the Second Dalek War, and in fact remained trapped in the ice for decades. (PROSE: The Whoniverse) Scholars of the incident devised different theories as to what ultimately happened to the army. In line with one theory popularised by Dalek historian Caul Pornell, (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) the Sixth Doctor directed Davros to Spiridon as part of a long game. Davros began converting much of the army into the first ranks of the Imperial Dalek faction, increasing their numbers from 10,000 to 4,000,000 in the process. The army allowed Davros to take the fight to the Dalek Prime, resulting in the hostilities of the Imperial-Renegade Dalek Civil War. (COMIC: Emperor of the Daleks!) A second account held that, during the Second Great Dalek Occupation, the Daleks of the Seriphia Galaxy attempted to pick up where their predecessors left off by creating an invisible army, but the Seventh Doctor infected them with light wave sickness and destroyed them. (AUDIO: Return of the Daleks) No matter the case, eventually, the only Dalek army left in hibernation was in the Fifth Galaxy. (WC: The Sentinel of the Fifth Galaxy)

During the Shoreditch Incident near the end of the Imperial-Renegade Civil War, the Seventh Doctor constructed a device to interfere with Dalek control systems, based on the device he previously used on Spiridon. (TV: Remembrance of the Daleks) When he attacked the Imperial Daleks with the device, one of them immediately recognised the technology from Spiridon, and knew it was the work of the Doctor, right before it was blown up. (PROSE: Remembrance of the Daleks)

The Doctor's warning to the Thals about not romanticising war did not become a lesson that all Thals took to heart. During the battle against the Dalek Eighth Fleet on Terakis, the Thals under Delani's command demonstrated warmongering tendencies by deploying a planet buster bomb, wiping out the Eighth Fleet as well as the natives of Terakis. Delani was prepared to make more such decisions, and was branded a war criminal by the crew of the Quetzel. Delani was ultimately killed by one of his subordinates, Ayaka, who could no longer bring herself to follow his orders. Ayaka was a descendant of Rebec, after whom her daughter was named. (PROSE: War of the Daleks)

Confronting after learning that he had survived his execution by the Dalek Prelature, the Dalek Litigator accused him of betraying "the Draconian Gambit, the army on Spiridon". The Master retorted that he chose to abandon those strategies as they "weren't working". (AUDIO: Vengeance)

Another historical account, The Dalek Conquests, also suggested that the Time Lords' act of sending the Doctor after the Daleks contributed to the eventual outbreak of the Last Great Time War. (AUDIO: The Dalek Conquests) The Time Lords soon took an increasing interest in the Daleks. They later sent the Doctor on numerous missions against the Daleks without the Doctor's initial request. (TV: Genesis of the Daleks, COMIC: The Dalek Revenge) In response, the Daleks gradually expended further time and resources in actions directed against the Time Lords, (COMIC: Return of the Daleks, TV: Resurrection of the Daleks, Remembrance of the Daleks, AUDIO: The Apocalypse Element, PROSE: Prisoner of the Daleks) many developments of which culminated in the Time War. (AUDIO: The Dalek Conquests, PROSE: A Brief History of Time Lords)

During the Time War, the Time Lords believed that the Spiridon army was still frozen. Recognising the threat of the Daleks excavating this army for use against Gallifrey, it was recommended that reconnaissance TARDISes make regular sweeps of the Spiridon system, and that any increase in Dalek activity on the planet be reported to the War Council immediately so that appropriate action could be taken. (PROSE: Dalek Combat Training Manual)

Some of the Daleks who survived encounters with the Doctor on Spiridon were driven mad and ended up in intensive care in the Dalek Asylum. (TV: Asylum of the Daleks)

Behind the scenes

 * Planet of the Daleks, Emperor of the Daleks! and Return of the Daleks all deal with Dalek operations on Spiridon, so the "Spiridon campaign" could reasonably refer to any of them. In the novelisation of Remembrance of the Daleks, from which the name "Spiridon campaign" originates, the Daleks are said to have been experimenting with biological weapons, corresponding with the mission from Planet.
 * The Discontinuity Guide claimed that the Daleks' Draconian Gambit and the Spiridon campaign took place after the Exxilon Gambit, which itself followed their unrecorded first encounter with the Third Doctor, which fell somewhere between the 23rd and 25th centuries. 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.
 * The Dalek Handbook suggests that the Daleks who waged Operation Divide and Conquer and the Spiridon campaign were time travelers from the future attempting to overwrite their own history, observing that a new hierarchy with grey Dalek drones, who had only identified the Third Doctor in the Time Paradox Incident, succeeded the silver Daleks following the 41st century Dalek Civil War which itself followed the Time Destructor Incident of 4000. It is further speculated that the silver Daleks in the Exxilon Gambit were 27th century-native Daleks who had been subsumed into the future Dalek forces.
 * It is also suggested that the Time Lords had ignored the Daleks' original wave of conquests and their development of time travel technology before the combination of the Daleks' large-scale efforts to alter history along with the Master's alliance with them and the Doctor's subsequent appeal for help motivated the Time Lords to notice the Daleks, foreseeing the potential future which led them to enacting the Genesis Incident.