During the Cold War between the Galactic Republic and the Sith Empire, Zadd was the location of a large contingent of renegade droids. The danger they posed was great enough to warrant a full-scale operation, which involved sending a special team to the surface to investigate and eliminate the threat while fighters would provide air support as necessary.
When the strike team landed, they battled their way through the complexes there, learning as they went of how Mentor, a droid supercomputer, had become sentient and stopped working for the benefit of humans. After recruiting others to his cause pro-droid equality, he set up a free, equal society for all the droids on Zadd. At some point, Mentor began absorbing the droids into a robotic hive-mind as he became increasingly obsessed with destroying all organics, eventually planning to broadcast a signal converting all droids in the galaxy into extensions of his will. The strike team moved swiftly to shut Mentor down before the signal could be sent.
Following the destruction of Mentor by the strike team, the moon's geothermal power core overloaded, resulting in its destruction.
Zadd was the site of the Flashpoint called Directive 7 in Star Wars: The Old Republic.
- Star Wars: The Old Republic Encyclopedia