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 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 Doctor described this event as "ten 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 Sontrans involving themselves in the Millennium War of 150 million years before. Later, in 2009, the Doctor gave yet another contradicting date for the war's beginning - 50,000 years before the 21st century.

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 Doctor. (DW: The Time Warrior)

In 1900s, a Rutan scout also attempted to take the planet Earth, this time for the Rutans. He was also stopped by the Doctor. (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 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 Doctor) and so set about invading Earth turning it into a cloning world. (DW: The Sontaran Strategem/The Poison Sky)

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)

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.