Gallifreyan Civil War

There were at least two Gallifreyan Civil Wars, both engendered by Pandora.

One happened when Pandora tried to make Gallifrey use its temporal power to change the Web of Time for her own ends. She was captured and dispersed so completely that she never existed. However, a portion of her consciousness survived in the Matrix. Over time, Pandora gained strength and tried to escape. This was prevented by Leela and K9. (AUDIO: Lies)

However, Darkel later released her, and she took the form of Romana's first incarnation. This led to the next civil war. (AUDIO: Pandora, AUDIO: Imperiatrix) This time she was defeated by Romana II. (AUDIO: Warfare)