Commander Gareth was the leader of the Rand Protectorate, one of the two major nations on Tegalus.
Biography
He greeted SG-1 to the planet, after they discovered the use of their Stargate. However, he learned that Soren, a religious leader attempted to take over Rand and attack Caledonia. The Caledonians launched a pre-emptive strike to take down their military installations, as the forces won't falter, and leave them under control of Soren. After he successfully took over the command bunker, Soren had Gareth captured, and executed him, and his soldiers. (SG1: "Icon")