Rutan-Sontaran War

The Rutan-Sontaran War between the Rutan Host and the Sontaran Warburg lasted for millions of years across Mutter's Spiral.

Origins of the War
The Sontarans, at that stage not yet a species of clones, but already, according to the Seventh Doctor, a "fierce, martial race", began to sweep over Mutter's Spiral. Only the Rutans stopped them. Reacting to this, the Sontarans stopped reproducing naturally and began to turn themselves into a clone species. (DWM: Pureblood)


 * The Seventh Doctor described this event as "10 centuries" before the 25th century, meaning that the conflict would have begun in the 15th century. This contradicts evidence given elsewhere, such as a Sontaran speaking of war with the Rutans in the 12th century as well as both Rutans and Sontarans involving themselves in the Millennium War of 150 million years before. Later, in 2009, the Tenth Doctor gave yet another contradicting date for the war's beginning - 50,000 years before 2009, which would give the date as 47991 BC.

Events in the War
During the 13th century, the Sontaran Linx claimed Earth for the Sontaran Warburg, though he was unable to hold the planet, being killed after being stopped by the Third Doctor. (DW: The Time Warrior)

In 1605, the Sontaran Empire and the Rutan Host discovered a distress beacon of a Rutan ship carrying two doomsday weapons capable of wiping out an entire species that had crashed on Earth four hundred years previously, and after discovering it, both the Sontarans and the Rutans raced to retrieve the weapons and use them on the other species. The Eleventh Doctor modified both weapons and gave one to each race, telling both that if one attempted to use it, they faced a possibility of killing their own species instead of the enemy. (VG: The Gunpowder Plot)

In 1900s, a Rutan scout also attempted to take the planet Earth, this time for the Rutans. The Fourth Doctor prevented him from doing this. (DW: Horror of Fang Rock)

In the 1980s, the Sontaran Warburg investigated the possibility of using time ships in order to win the war. They attempted to gain the secrets of the TARDISes from the Second Doctor, but they were betrayed by Chessene of the Franzine Grig. At the same point in time, the Sontarans were involved in a battle with the Rutans in the Madillon Cluster, with the Rutans winning this conflict. (DW: The Two Doctors)

In the early 21st century, the Sontarans were apparently losing the war (based on speculation by the Tenth Doctor) and so set about invading Earth turning it into a cloning world. They failed and the Sontaran fleet was destroyed by Luke Rattigan. (DW: The Sontaran Stratagem/The Poison Sky)

Circa the late 21st century, the war saw conflict near the Sol system once again leading to the Rutans attempting to capture planet Earth. (QR: The Sontaran Games)

During either the 25th or 26th century, the Rutans destroyed the Sontaran homeworld, Sontar, with photonic bombs, though some escaped with the Sontaran racepool. (DWM: Pureblood)

In the 26th century the Rutans took over the colony of Chelsea 426 above Saturn by using spores from flowers to take over the people. However the Fourth Sontaran Intelligence Division tried to stop the Rutans and attacked the colony. Due to the Tenth Doctor's intervention, the Sontarans were victorious, although later there was evidence that one Sontaran had been taken over by the Rutans. (NSA: The Taking of Chelsea 426)

It's unknown if this took before or after the destruction of Sontar.

Involvement of Gallifrey
Gallifrey has been involved with the war in several instances. During the Dark Times, the Gallifreyan hero Prydonius was sent to act as an observer in the war. (NA: Cat's Cradle: Time's Crucible)

During another period of Time Lord history, the Warburg, led by General Sontar himself, the Warburg's supreme commander, and the Rutan Host convened on Gallifrey to meet face to face without violence. (PDA: The Infinity Doctors).


 * When these two encounters with the Time Lords occurred in unknown, due to the difficulty in dating the Time Lord stories.