The Chandrila executions was a secret order given by the recently promoted Dark Lord of the Decreton Empire Darth Krayt to his Hand Darth Nihl; instructing Nihl to execute the Sith defectors Darth Azard and his twelve comrades following their victory at the Battle of Chandrila.
The thirteen defectors were all Sith Lords who had defected to Darth Krayt's Sith Coalition following the death of Darth Proditor, and as such people Krayt could not place his trust in whatsoever.
Behind the scenes[]
The Chandrila executions were created to showcase Darth Krayt's ability to commit "disreputable acts" much more clearly than his actions during a battle. It also helps to point out his tactical genius; utilizing the defectors to destroy a rebel fleet before executing them.