Hugo Barton began working for the UNSC Navy's Office of Naval Intelligence in the 2530s. In March 2553, Barton was working at ONI Research Facility Trevelyan as Doctor Irena Magnusson's deputy. When Admiral Margaret Parangosky arrived to remove Dr. Magnusson as director of Trevelyan, Barton drove her to the portal. On the way she questioned Barton about how Jul 'Mdama was able to escape. She also informed him that he would take Dr. Magnusson's place as director of the facility. He accompanied Parangosky to the portal and was present when Dr. Magnusson was relieved of duty and detained.
Barton remained as the head of ONI's research facility on the shield world even as the scope of the project expanded to include the Swords of Sanghelios with the advent of the Onyx United Research Project. In 2554, Franklin Mendez, the project's head of security, told a UNSC soldier who had started a fight with his second-in-command, Kasha 'Hilot, and the squad who had watched, that they were being sent off the shield world. He told the soldiers to introduce themselves to Barton if they questioned his decision. Mendez said the next day he would talk to Barton about maintaining the standards for vetting soldiers to be stationed in Trevelyan to keep the fighting from happening again.
On June 21, 2557, Barton received an after-action report on an expedition taken by prowler UNSC Taurokado and Fireteam Apollo to the Korinth Prior system in search of UNSC Spirit of Fire. The prowler discovered the remains of the Etran Harborage and assumed that Spirit of Fire had been destroyed alongside the shield world. Having encountered Covenant forces in the system, Turkish, the shipboard AI of Taurokado, suggested to destroy the shield world's remains to prevent the Covenant from recovering technology. It was subsequently destroyed by a massive UNSC fleet as Turkish suggested.
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