The Galactic Empire had a secret garrison on the planet in the Valley of Umbra. New Republic operative Jai Raventhorn was captured by the base and interrogated. However, she escaped her imprisonment and took the commanding major captive. She forced the major to call Nul and expose the Imperial presence. It was likely that Nul then called an air strike on the garrison.
After the Imperial presence was exposed, Nul was convinced to join the fledgling New Republic.
- Planets of the Galaxy, Volume Two
- The Star Wars Planets Collection