The Judoon Captain was employed by Challoner of the Cosmic Peacekeepers to kidnap Edward VII in 1902.
This Judoon captain believed that Judoon honour was “without flaw or stain”. When the Tenth Doctor revealed to him that Challoner had forged documents authorising the Cosmic Peacekeepers' occupation of Earth he was furious at being betrayed and felt that his honour had been damaged. After ordering his forces to retreat, the captain shot and killed three Peacekeepers, and attempted to kill Challoner before the Doctor intervened.