Atraken

Atraken was a doonium rich planet conquered by the Confederacy of Independent Systems. The Galactic Republic tried to liberate it in 22 BBY and were only successful through a series of strikes called Operation Katabatic nearly a year later. The Separatists engaged in a "poisoned well" policy, releasing a biochemical plague into the planet's water table that killed 90% of the population. The survivors mostly relocated to Trilos, if not to other neighboring worlds. Thrynka Padaunete blamed the disaster on the Jedi.

The once beautiful planet had been left a desolate, bombed-out husk by the second year of the Clone Wars after eleven months of fighting. Its oceans, those that hadn't boiled away, were now large bodies of poisonous water and the poisonous air carried what remained of the chemical weapons that were used. The only life forms capable of living on Atraken were the 'diehards'; large burrowing insects that had adapted to eating the poison.

Text and facts from the “Atraken/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.