Sergeant Thompson was an officer in the Union Army during the American Civil War. He was abducted by the War Lords and hypnotised into participating in their simulated version of the war. He captured Jamie McCrimmon and Lady Jennifer Buckingham, believing them to be spies for the Confederate Army. He and his men abandoned Jamie and Jennifer after an attack by Confederate soldiers.
He, like all the surviving victims of the War Lords, was returned home by the Time Lords. (TV: The War Games)