General Otto Strasser was the commanding officer of the Britischer Freikorps in an alternate timeline. In 1951, the Seventh Doctor, posing as the Reichsinspektor General, met with the General and got him to provide the help he needed to get back his TARDIS and find out when the timeline had changed.
After returning from examining the military archives at the British Museum, Strasser informed the Doctor that Lieutenant Anthony Rupert Hemmings was leading a raid on Ma Barker's café. The Doctor told Strasser that Hemmings was about to ruin a delicate operation and the two of them arrived at the café, preventing Hemmings from making his arrests and arresting him instead. That night, Strasser learned that the Doctor was an impostor when the body of the real Reichsinspektor General was found, and that the TARDIS was a time machine when he had the Doctor's conversation bugged. Just as he was about to have the Doctor shot, Ace used her Nitro-9a against him and his men, killing them. (PROSE: Timewyrm: Exodus)