In 196 BG, few years after the League Armada's devastation of Earth, Bela Tegeuse was a random Synchronized World chosen for attack. With much fanfare the warships had gone out, led by Xavier Harkonnen.
The battle of Bela Tegeuse had destroyed many robots, attacked the Omnius stronghold and obliterated extensive thinking machine infrastructure, but the enemy fought back relentlessly.
Vorian Atreides had distinguished himself in that battle, earned a higher rank, and proved his true fervor for the cause of humanity; but had suffered so many losses that they were forced to withdraw without a clear-cut victory
A year later, Vorian self-willing and without orders, went to inspect the Tegeusan system and reported that the machines had rebuilt everything and continued to oppress the surviving human population there.
- Dune: The Machine Crusade (Mentioned only)