Like the title says, I was playing a 1.7 game and suddenly there was a huge crash sound like when you lose a resource. Except that my newest town was suddenly completely wiped out.

To give some background: A few turns earlier, it was taken by an enemy. I immediately took it back then moved my army out to deal with enemy forces attacking my outposts. That's when I heard the crash and lost the city but I got no kind of alert or warning of what was happening. I am assuming that it was a spell of some sort since there were no enemies in the vicinity when I moved back there.

Is there some kind of log I can access to see what happened? 

Thanks in advance for any insight offered.