At some point he had become seriously ill. When his own doctors were unable to treat him, his ministers appealed to the Federation for help. That help, in the form of the USS Enterprise, under the command of Captain Christopher Pike, arrived shortly afterwards. Pike felt that to save Harath's life might lead to an improvement in the relations between Harath and the Federation.
Pike, Dr. Phillip Boyce and Mr. Spock beamed down to Harath's palace, where Boyce was able to quickly treat Harath. Boyce was considerably upset that he was able to treat Harath, and found himself questioning whether or not he should have ended Harath's life. (TOS novel: Legacy)