The Eternal Battle (audio story)

 was the second story in the sixth series of The Fourth Doctor Adventures, produced by Big Finish Productions. It was written by Cavan Scott and Mark Wright and featured Tom Baker as the Fourth Doctor, Lalla Ward as Romana II and John Leeson as K9 Mark II.

Publisher's summary
The TARDIS has landed in a war zone. The Doctor, Romana and K9 find themselves traipsing through an inhospitable battlefield. Strange lights flicker in the sky, and stranger creatures lurk in the darkness.

When rescued from an attack by a Sontaran tank, the time-travellers discover they’re facing a far more dangerous foe than the battle-hungry clones. This terrifying fight has been going on longer than anyone can remember... and shows no signs of stopping.

With the TARDIS missing and their luck running thin, the Doctor and his friends’ only hope of survival is to uncover the truth about what is happening on this planet. If they can discover the secret of the eternal battle they might just survive... but it might just mean the end of them all.

Part one
En route to the Lake District, the Doctor, Romana and K9 find themselves on a desolate, rain-sodden world along with a squad of battle-weary Sontarans.

The Sontarans are fighting a campaign on two fronts: Against crazed, undead humans on one side, and crazed, undead Sontarans - their former allies - on the other.

Strange lights appear sporadically in the sky, but the Sontarans seem completely unaware of them.

When the TARDIS goes missing, the Sontarans agree to join forces with the time travellers.

Using a Sontaran communicator, the Doctor is able to detect chronon pulses coming from the likely relocation of the TARDIS - behind enemy lines. The Doctor and Major Stom set off in a Sontaran tank to retrieve it.

Meanwhile, Romana and K9 examine the recently deceased body of Sontaran trooper Varn, detecting some sort of time element to the zombie disease. As they continue the examination, the undead Sontaran suddenly reanimates and attacks.

The Doctor and Stom arrive at their intended location, but instead of finding the TARDIS, they find a transmitter - a projection node - buried in the mud.

A platoon of human soldiers suddenly appears, and their leader gives the order to execute.

Part two
Using the projection node, the Doctor transports himself and Stom to a control centre operated by the Sycon - alien beings from the far, far future.

The Sycon have time-looped hundreds of battles and skirmishes throughout history, to teach their society the futility of war.

However, after operating for thousands of years, the battle matrix is out of sync. Instead of the time-bubbles being reset, the dead combatants are respawning as undead monsters.

The TARDIS is also at the Sycon control centre. When it detected it had landed in a time bubble, it activated emergency maneuvers, then contacted the Doctor through the time bubble's projection node.

Lenk rescues Romana and K9 from the undead Sontaran, while the human soldiers requisition the abandoned Sontaran tank and launch an attack on the Sontaran base. Lenk resolves to destroy the entire base in a bid to wipe everyone out.

The Doctor reveals the truth to the Sycon AI - the Sycon themselves were wiped out in a war long ago, their planet too is now just a desolate wasteland.

The Sycon resolves to shut down the time-bubbles, destroying all within. The Doctor convinces the Sycon AI to instead deactivate itself, saving the combatants within the bubbles.

The Doctor and Stom rescue Romana and K9 before the Sontaran base explodes.

Stom and the survivors of the time bubbles must now make the abandoned Sycon planet their new home. Stom allows himself to be rendered unconscious by the Doctor, allowing the time travellers to leave in peace.

Cast

 * The Doctor - Tom Baker
 * Romana - Lalla Ward
 * K9 - John Leeson
 * Field Major Lenk / Sergeant Major Stom - Dan Starkey
 * Captain Nina Albiston / Sycon Computer - Jane Slavin
 * Brennan / Trooper Varn - John Banks

Time technology

 * A temporal projection node generates a time bubble and creates a time field, also called a "chronal field," trapping the Sontarans and humans in a time loop, which the Sycon computer calls a "pocket continuum".
 * If the pocket continuums are shut down, all subjects within would be atomised and scattered into the time vortex.

Sontarans

 * Lenk comments that a Sontaran being afraid of death is disgraceful. For a Sontaran, there is either battle or death in battle.
 * All Sontaran battalions have orders to shoot the Doctor and his associates.
 * The Doctor comments that "trench warfare," in the rain and the mud, is not the Sontarans' style.
 * The Sontarans make use of tanks, which are vanguard-class heavy assault units, armed with concussic chambers.
 * Sontarans face battle "eyes forward, probic vents behind."
 * Lenk's forces were ordered to annex an occupying force of humans on the planet, a "backwater colony world" which the Doctor comments as a "couple of parsecs" from Earth. The humans had automated battlements.
 * The Sontarans have been battling the undying forces for years or decades, but he cannot remember.
 * The Doctor mentions a Sontaran Academy.
 * Stom prefers grenades for weapons. He becomes the last Sontaran in a time period where Sontar doesn't exist.

Sayings

 * Romana quotes "All quiet on the Western Front".
 * The Doctor says "X marks the spot".
 * Upon obtaining a Sontaran tank, Albiston claims "this is a red letter day".
 * The Doctor begins to choose a control by saying "Eeny, meeny, miny, moe, catch a Kaled by-"
 * He refers to the computer as the "ghost in the machine".
 * He says he's very good at "jiggery pokery".
 * The Doctor remarks that all computers say "insufficient data" when they don't want to admit they're wrong.
 * Romana quotes "the shoe's on the other foot" and the Doctor quotes "turn the other cheek".

Sycons

 * The Sycon race is from millennia in the future, from the universe's "twilight years", when the Sontarans are extinct. The Doctor describes them as peace-loving.
 * By the new calendar, the Centre of Academic Excellence was established in the year 97391 in New New Canada.
 * To illustrate "the futility of war," subjects were gathered by technology similar to a Time Scoop, taken from battles throughout history, but no major wars, so as not to attract attention. Visitors from every major race in the cosmos were to be invited to observe.

Continuity

 * Romana is familiar with Sontarans from their invasion of Gallifrey. (TV: The Invasion of Time, PROSE: The Shadow of Weng-Chiang)
 * The Doctor mentions the Rutan Host, (TV: The Time Warrior, Horror of Fang Rock) and vampires. (TV: State of Decay)
 * The Doctor mentions Dunkirk. The First and Eighth Doctors were present at Dunkirk. (PROSE: Just War, Byzantium!, AUDIO: Fugitives)
 * The Seventh Doctor would later encounter another group of scared Sontarans. (AUDIO: Terror of the Sontarans)
 * The Doctor comments that he's never had a Sontaran as a companion. He'd later befriend the Sontaran nurse Strax, (TV: A Good Man Goes to War, The Name of the Doctor, et al.) and travel with him in the TARDIS. (COMIC: Time Gentlemen, Please!)
 * Albiston believes in a goddess, as did Benny Summerfield. (AUDIO: The Shadow of the Scourge)
 * The Doctor says some of his best friends are soldiers, including the Brigadier. (TV: The Invasion, Spearhead from Space, et al)