Thot Gor was the representative of the Breen Confederacy to the Dominion in 2375. As the Dominion War grew to a stalemate in mid-2375, Gor was secretly approached by the Female Changeling for an alliance between the two powers. Seeing an opportunity for conquest, Gor traveled to the Cardassian Union to sign the treaty of alliance. En route, his ship captured Lieutenant Commander Worf and Lieutenant Ezri Dax, who had been stranded on a planet in the Goralis system.
With the addition of the Breen forces, the balance of power in the war was shifted in the Dominion's favor. Thot Gor oversaw the Breen forces, quickly coming to outrank Legate Damar of the Cardassian Union in the Dominion hierarchy, an event which incensed Damar greatly. One of Thot Gor's first actions was the daring attack on Earth. He later oversaw the Second Battle of Chin'toka, which was a remarkable victory for the Dominion.
Following the retaking of Chin'toka, Gor was succeeded by Thot Pran as commander of the Breen forces.