Q:

Looking for details on historical math anecdote

My memory is very sketchy here so bear with me. A fairly prominent 19th or 20th century mathematician was captured by a military force, probably invaders. He claimed that he was just a civilian, a mathematician, and in order to prove that he was a non combatant he had to talk about, what was at the time, cutting edge mathematics. Anybody know who this was and can link me to more details? 

A:

It's an apocryphal story about the Russian mathematical physicist and Nobel Laureate Igor Tamm. In the story, he was said to stopped by highwaymen and was released upon answering a quiz question about Maclaurin Series.
The story is recounted here, though the quoted source is down. At this site we see the same story, but this time he is suspected of being a communist agitator 
His Wikipedia page can be found here

