Thomas Fitzgerald was the captain of the HMS Thunder a Royal Navy submarine during World War II. In 1941, the Seventh Doctor and Ace helped Captain Fitzgerald and his crew to rescue survivors from the sunken HMS Intrepid Ranger and dispatch a preying U-boat. However, the Thunder was hit by a torpedo and began to sink. The Doctor and Ace departed to prevent changes to history as the endangered crew evacuated. (AUDIO: Dark Convoy)