There is the story about Sir Humphrey de Bohun, who was a nephew of the English military leader . In an announced battle of the Scotiish against the English, he discovered the Scottish king, Robert the Bruce, to be alone and unguided, sitting on a pony!
He attacked him and the king turned his pony just in time to reveal an axe on the other side and defending himself just in time.
I've always wondered if it was a very obvious trap, or if the king really was this careless.
I've taken it from a magazine about Scottish history.