At the onset of the show, he is involved in a sexual relationship with a blonde woman. Believing her to be working for a corporation in the defense industry, and desiring a more permanent relationship with her, he gives her access to the highly classified Colonial defense mainframe (an act of treason punishable by the death penalty) so her employers can have an advantage in future contract bidding. In exchange for his access to the government mainframe, she helps him design a navigation program used by Colonial warships, covertly creating backdoors in the program. When the Cylons attack the Twelve Colonies, they use those backdoors to penetrate software security firewalls, disabling entire fighter squadrons outright and sabotaging vital capital-ship systems. On the day the Cylons attack humanity, the woman reveals she is an advanced Cylon, model Number Six (later known as Caprica Six), and she used the information that Baltar gave her to shut down the Colonial defenses, thus making him responsible for the Cylons' successful genocidal campaign against the Twelve Colonies. Baltar manages to survive the nuclear explosion that destroys his home due to Caprica Six using her body to shield him.