Miyamoto Musashi - Myths & Legends

Q - Was Musashi ever defeated?

A - It seems unlikely.  There is a record of a defeat during a rematch with Muso Gonnsuke of the Shinto Muso-ryu, but this record only exists in Gonnosuke's school whereas the original duel was recorded in many sources of the time.  As Gonnosuke was quite a famous combatant and a victory against Musashi would've been massively beneficial to him, it is highly unlikely that he would have fought a rematch without an audience to witness any victory of his.