Commander Gareth was the leader of the Rand Protectorate on the planet Tegalus when SG-1 was their first contact with people from another planet. (8.05 "Icon")
The Rand Protectorate and the Caledonian Federation were already posed to destroy each other when SG-1 arrived. Any more tension between the two countries could end in disaster. Unfortunately, just as Gareth attempted to appease Minister Treydan of Caledonia with the news of the Stargate and Earth, Treydan immediately suspected Gareth from keeping vital information about the Stargate and the "offworlders" from him and his scientists.
The religous group who followed the old scriptures which said that the gods would return through the Great Ring of Avidan (the Stargate) and reward the faithful were fired up by SG-1's arrival. All of their scriptures seemed to speak the truth. Their leader, Soren, took advantage of the situation and rallied his followers in a revolution. They took Rand's underground bunker where the Stargate had been moved and executed Gareth on the spot.
With the help of the SGC, Jared Kane, Gareth's chief aide, commanded a small group of men and took back the bunker. Kane killed Soren as soon as he was able, most likely as recompense for Soren's cold-blooded assassination of Gareth. The peace that the Rand Protectorate had after their retaking of the bunker was short-lived, and eventually, the two countries destroyed each other, leaving the Stargate buried in the rubble. (8.05 "Icon", 9.15 "Ethon")
--DeeKayP 17:21, 10 Aug 2004 (PDT)