Great Catastrophe (The Exterminators)

The Great Catastrophe was a devastating event that engulfed the galaxy which saw the widespread destruction of all the Daleks and their technology.

This occured when Susan Mendes accessed the Dalek Empire's command net through the Dalek Emperor and activated their self-destruct sequence. Whole star systems were destroyed and countless lives were lost. In time, the event became legends that were passed throughout the planets of the galaxy. These legends spoke of a figure known as the Dark One or the Bringer of Death who was responsible for the Great Catastrophe. (BFA: Dalek Empire II: Chapter Four)