Eternal War

The Time Lord-Vampire War was a protracted and extremely bloody conflict fought early in the history of the Time Lords, against the Great Vampires.

History
The war took on the status of a legend throughout most of the universe, with few exact details known. The origins of the Great Vampires were unknown, as was the precise reason for the conflict between Gallifrey and them.

Rassilon's leadership had revolutionised Time Lord society; it is possible he launched the war on purely moral grounds. Whatever the cause, the ferocity and resilience of the Vampires made their defeat very difficult, even for the Time Lords. Conventional weapons were virtually useless and at this point the Time Lords did not have access to some of the more spectacular armaments they later developed.

The weapon which won the war was the bowship. This was designed to exploit the one weakness of the Great Vampires - their vulnerability to being impaled through the heart. Nevertheless, hunting down the entire species was a protracted business and the leader of the Great Vampires was never found, although much later it was discovered he had escaped into E-Space.

The war caused such widespread loss of life that the Time Lords rejected the use of violence forever. They did not, however, adopt their non-interference policy for some time after this. (DW: State of Decay)

After the Vampires' defeat, their legend and elements of their story existed in many cultures, including Earth, where Vampire legends also existed among the populace. (MA: Goth Opera, EDA: Vampire Science)

The Fourth Doctor effectively ended the war by killing the King Vampire, who had fled into E-Space. (DW: State of Decay)