From Halopedia, the Halo wiki
Gough was serving on the UNSC Pillar of Autumn in 2552, which crash-landed on Installation 04. There, Gough and the rest of his squad were to infiltrate a Covenant held bunker. Gough and two of his squadmates drove there on a Warthog, Gough riding shotgun, while the other three members got there on foot.
Gough and the rest of the squad broke into the bunker, but lost Segur in the process. He and McLees were tasked with guarding the entrance door to the bunker. They failed in their attempt to help their sergeant, who was ambushed and killed. Gough escaped in a Ghost, while McLees covered him. Followed by two Ghosts and Banshees, his Ghost got shot down, however he was saved in time by the Master Chief. The two of them were the only survivors of the mission.
He was named after Charlie Gough, one of the programmers in Bungie.