Defence of Gallifrey

The Defence of Gallifrey was the final battle of the Kotturuh crisis in the Dark Times. It was mounted by three incarnations of the Doctor, in command of the remains of the Victis Fleet, to save their homeworld from the Dalek Time Squad. The Squad had been ordered to destroy Gallifrey before the rise of the Time Lords as part of the Dalek Emperor's contingency plan, codenamed as the "Ultimate End". (PROSE: All Flesh is Grass)

Prelude
After declaring himself Time Lord Victorious, the Tenth Doctor fled to the Dark Times via a Time Fracture, where he decided to stop the Kotturuh from spreading death, eventually devising a necrotic virus which reduced their lifespan to just fifteen minutes. (PROSE: The Knight, The Fool and The Dead) His interference led to temporal fluctuations which altered timelines across the universe, (PROSE: The Guide to the Dark Times) which affected the Dalek Restoration Empire, appearing to prevent them fighting the Last Great Time War. (COMIC: Defender of the Daleks) After becoming aware of the Doctor altering history from an ancient Dalek drone, (PROSE: The Last Message) the Dalek Emperor created the Time Squad to investigate and rectify the fluctuations to the Daleks' advantage. (PROSE: The Guide to the Dark Times) The Time Squad recruited the Eighth Doctor to help them correct the timeline, with him enabling them to reach the Dark Times by connecting his TARDIS to their saucer's engines. (AUDIO: The Enemy of My Enemy)

Their investigation led to them to the Kotturuh home planet, Mordeela, where they confronted the Victis Fleet, a mercenary force the Tenth Doctor was leading to finish off the Kotturuh, alongside a Free Undead coffin ship commanded by the Ninth Doctor, who were also investigating the rewriting of history. In the ensuing Battle of Mordeela, the Daleks and Vampires reduced the Victis Fleet to just the flagship, but the Tenth Doctor was able to destroy the planet as planned and fled. (PROSE: All Flesh is Grass) The Daleks believed they had failed to correct the timeline, so began a back-up plan of harvesting lifeforms unique to the Dark Times to weaponise them. (PROSE: Mission to the Known) The Daleks eventually targeted the Vampires for their experiments, attacking the Ninth Doctor's coffin ship, but the Eighth Doctor took the opportunity to escape by forwarding the Undead so they could evacuate and fleeing with his future self. (PROSE: All Flesh is Grass)

Afterwards, the Dalek Time Commander and Executioner received pre-recorded orders from the Emperor for the event of failing to correct history. He ordered them to take advantage of their presence in the Dark Times by destroying Gallifrey to prevent the rise of the Time Lords. (PROSE: Mission to the Known) The Dalek Prime Strategist was not privy to the new orders, so continued the experiments with the Scientist, focusing on creating a more biologically efficient form of Dalek - the Symbiont. As the Daleks prepared for enacting the Emperor's orders, referred to as the "Ultimate End", the Commander dispatched scout ships to finish off the last of the Kotturuh, fearing their judgement on the Daleks.

A Dalek scout ship was sent to Entranxis to capture Ikalla, a Vampire who had escaped the Doctor's coffin ship, for the Symbiont experiments. They encountered the three Doctors there, who helped Ikalla escape. Their target lost, the Daleks set Entranxis' atmosphere alight. This was witnessed by the Eighth and Tenth Doctors aboard the Tenth Doctor's ship, now known as the HMS Donna, and they resolved to stop the Daleks they had unleashed on the Dark Times. They pursued the Daleks and discovered they had attacked a coffin ship, capturing the Great Vampire it had been transporting. With the aid of the coffin ship's Bloodsmen, the two Doctors and Brian the Ood infiltrated the Dalek saucer. The Tenth Doctor discovered the Strategist's experiments, infusing Great Vampire DNA into a Dalek mutant to create an undead Dalek, whilst the Eighth Doctor and Brian went to the bridge. There, the Eight Doctor teased the Commander until he learnt he had just sent a scout ship to kill the last of the Kotturuh on Birinji. The Strategist's experiments caused an unanticipated power drain, enabling the Doctors to escape and Brian to hide in the engine room. The Doctors rallied the Donna to destroy the scout ship as it approached Birinj, reuniting with the Ninth Doctor and Ikalla, who had been visiting the last of the Kotturuh, Inyit.

The Commander reprimanded the Strategist for the power drain, claiming it had jeopardised the Ultimate End. The Strategist countered it could not jeopardise plans he had been unaware of and presented the finished Symbiont. Brian ended up in a standoff with the Daleks by connecting a explosive to the engines, which would detonate if they killed him. From the engine room, he learnt the co-ordinates of the Daleks' destination and communicated it to the Doctors, who quickly recognised it as the location of Gallifrey. They decided to mount a defence, mobilising the Donna and three coffin ships of the Free Undead whilst Ikalla remained to look after the ailing Inyit. The Tenth Doctor used his TARDIS to rescue Brian, leading to the Strategist realising that the Doctors were aware of their plans and would defend Gallifrey. In preparation for the coming battle, he ordered for the Silver Dalek Drones to be given Symbiont DNA, making them undying, whilst the original Symbiont was dispatched to Birinji to kill Inyit. (PROSE: All Flesh is Grass)

The battle
To be added

The end of the Dalek Time Squad
The Eighth Doctor survived the explosion aboard the Dalek saucer using a personal heat shield he hsd acquired on Atharna. With the Daleks believing him dead, though the Strategist suspected otherwise, he began sabotaging their saucer in such a way it appeared as a series of malfunctions. The Time Squad was divided in their response; the Strategist worked with the Scientist to stabilise the vessel so they could leave the Vortex, whilst the Time Commander suspected alien sabotage and gave the Executioner autonomy to purge the ship of all aliens and had the Doctor's TARDIS brought to the bridge. The Scientist diverting power led to the awakening of two alien prisoners who had been in cryogenic suspension, Tiska and Groth. The Doctor interrupted the Scientist's work by infiltrating its laboratory and sabotaging the artificial gravity there. He teased the Scientist into telling him about the prisoners and secretly planted an explosive he had made using the heat shield on it.

He found the prisoners and helped them escape the Executioner, which was now rampaging through the saucer, damaging the ship and fellow Daleks in its insanity. The Commander was unable to rein it in, to the Strategist's frustration. After Groth was killed by the Executioner, the Doctor and Tiska reached the bulkheads, which enabled the Doctor to detonate his explosive. The explosion killed the Scientist and exposed half of the saucer to the Vortex, killing the Executioner, and caused the ship to begin breaking apart. The Strategist sought the Doctor to bargain with him for safe passage in his TARDIS. He played along, but exposed the deal to the Commander, leading to a firefight between the two Daleks. The Strategist prevailed, but the Drones turned on him as a traitor. This enabled the Doctor and Tiska to flee in his TARDIS. (AUDIO: Mutually Assured Destruction)

As the Dalek saucer broke apart, the Daleks were torn apart by Time winds. The Strategist observed their deaths and reflected on the events that had led him there, believing, if he had been aware of the Ultimate End, he would have warned the Emperor against it. He used Kotturuh crystals he had stored in his casing to power an emergency temporal shift to escape the Vortex, intending to aid or replace the Emperor in the war against the Time Lords that he believed was now inevitable. (PROSE: Exit Strategy)

Causal loop of the Kotturuh crisis
One Drone also survived, ending up adrift in space. It sent the message that originally embroiled the Daleks in the crisis (PROSE: The Last Message) and was eventually discovered in the Oort cloud and brought aboard the Starship Future in 2985. There, it rebuilt its casing and attempted to cultivate a new Dalek army from the dormant colonists aboard, but was stopped by the Fourth Doctor, who it attempted to forewarn about his future to avert the Eighth Doctor's destruction of the Time Squad. He believed it defeated and left, but the Dalek had actually survived again. (AUDIO: Genetics of the Daleks)

A message from this Dalek eventually reached Skaro shortly before the Drone had left, causing the Daleks to initiate the Invasion of the Archive of Islos. (PROSE: The Last Message)

Reconciliation on Birinji
After the Dalek saucer was forced away, the Tenth and Ninth Doctors took a moment to look at their homeworld, which they believed destroyed in their time period, and then abandoned the Donna. It burnt up in Gallifrey's atmosphere whilst they returned to Birnji in their TARDISes. With Inyit having passed away before they could return, the Tenth Doctor finally conceded he had gone too far in rewriting time and expressed his remorse. Inyit had passed the last of her energies on to Ikalla, averting her fear about uncontrolled death escaping and making Ikalla into "something new". The two Doctors realised that death would still enter the universe without the Kotturuh, but would do so entirely naturally. Though happy with that change, the Tenth Doctor agreed not to alter history any further and the two incarnations reconciled.

Ikalla summoned the Free Undead to settle on Birnji and became their scion, freeing them from the fates of their former masters. Whilst the Ninth Doctor went to reunite with Rose Tyler, the Tenth Doctor departed the Dark Times alone, as Brian had decided to remain on Birinji. (PROSE: All Flesh is Grass)