Cloister Wars

The Cloister Wars were an amount of conflicts mentioned by to Clara Oswald when explaining how long she had cared for the Doctor. She also mentioned "the night he stole the moon and the President's wife", and that it had also been so long it was "since he was a little girl". She then stated that one was a lie, and asked Clara if she could tell which one. (TV: The Magician's Apprentice)