Lieutenant Tom Carver was a soldier.
He and Group Captain Gilmore were in the same Royal Air Force unit, where Carver was second-in-command. Their unit, of which they were the only survivors, was part of Operation Market Garden. Carver was severely shell-shocked following his experiences. This led to his wife divorcing him and taking their daughters with her. According to Gilmore, he drank heavily but not on duty.
Carver went through Professor Heinrich Schumann's matter transfer device. Like Schumann, he was possessed by an alien intelligence during transmission. However, he was able to re-assert control long enough to sacrifice himself to save Gilmore, Professor Rachel Jensen and Dr Allison Williams. (AUDIO: Threshold)