Battle of Arkheon

The Battle of Arkheon was one of the last engagements of the Second Dalek War. Launched by Earth Command, the path to the attack was paved by the loss of the Exterminator. (PROSE: Prisoner of the Daleks)

Destruction of Arkheon
Arkheon was among many planets destroyed during the First Dalek Incursion. Unknown to the Earth forces, the Daleks occupied its ruins in search of a time rift known as the Arkheon Threshold and established a top secret, maximum security prison facility beneath the surface. When the Daleks sought to utilise time travel to turn the tide of the war, they attempted to breach the Arkheon Threshold to break into the Time Vortex and alter human history from its very beginnings. (PROSE: Prisoner of the Daleks)

Mission to Arkheon
When the Tenth Doctor and Jon Bowman's crew aboard the Wayfarer caught wind of this, they embarked on their own mission to Arkheon to secure the Threshold first, unaware the Daleks were already there. Made prisoners, they were interrogated and tortured by the Dalek Inquisitor General, Dalek X, who intended to use their knowledge to complete the Dalek experiments. (PROSE: Prisoner of the Daleks)

Loss of the Exterminator
The Doctor eventually engineered their escape by taking advantage of the Daleks' shortcomings in time travel capabilities. Ostensibly offering them the use of his TARDIS, he escaped when the Daleks brought him to Hurala to recover it. He subsequently detonated the leftover astronic fuel in Lodestar Station 479, totally obliterating the Exterminator and the Temporal Research Team. (PROSE: Prisoner of the Daleks)

"Seize Arkheon"
Without the Exterminator, the rest of the Dalek Fleet fell into complete disarray and the Earth Empire was able to start pushing them back. Bowman returned to Earth with the Doctor and gave a report of the events on Arkheon and Hurala to Earth Central. Earth Command swiftly organised a new operation, intended to "seize Arkheon and liberate the prisoners" within the facility. The Doctor remarked that such an undertaking "could be quite a battle". After receiving a full pardon for his desertion earlier in the war, Bowman was offered the chance to lead the attack, but he declined in favour of retirement.

An Earth squadron was dispatched to Arkheon. Soon they were victorious and achieved all their objectives. The prisoners were freed and the Dalek base was cleaned out. The Doctor followed on and sealed the Arkheon Threshold to prevent any further nefarious attempts to exploit it.

The loss of Arkheon and closing of the Threshold put paid to any further Dalek bid to win the war via time travel, although the destruction of the Temporal Research Team before that had already signified the killing blow. The Supreme Dalek on Skaro was forced to abandon the strategy.

The Doctor returned to Hurala to find Dalek X, the only survivor of the loss of the Exterminator, and informed him of the outcome. Due to Dalek X's part in these events, the Doctor warned the Inquisitor General that the Supreme Dalek was unlikely to be in a forgiving mood should Dalek X ever return. (PROSE: Prisoner of the Daleks)

The Second Dalek War thereafter drew to an "untidy conclusion" and ultimately "fizzled out". (PROSE: Deceit)

Behind the scenes

 * The exact name "Battle of Arkheon" is never used in Prisoner of the Daleks but the Doctor acknowledges that a battle is bound to take place there after he hears the plan. Based on dialogue of this kind, Seizure of Arkheon or Liberation of Arkheon are other potential names, although all are still subject to conjecture.