Great Cleansing

The  on Baspral was a time of riots, war, and mass executions. It was led by a man who had almost been drowned by the seer Galena as a boy and who in turn drowned her ten years later.

The long term results of the Great Cleansing were that Basprali laws changed for the better and that Baspral was better equipped to withstand a Dalek assault some time later. (PROSE: The Inquisitor's Story)