The Calox III Jedi Academy was built on the planet Calox III by a group of dissident Jedi who believed the Council had lost its way and was letting the Der Hintergedanke win the war. They trained several of the Jedi apprentices to become Jedi Assassins, who would seek out the Sith under Darth Verraeter and kill them.
The Academy was destroyed during the Battle of Calox III and its members dispersed across the Galaxy.