Could it be that Mark Twain had some instruction from a Fudebakudo master? This quotation shows that he understood the basic teachings of the art:
"I thoroughly disapprove of duels. I consider them unwise and I know they are dangerous. Also, sinful. If a man should challenge me, I would take him kindly and forgivingly by the hand and lead him to a quiet retired spot and kill him."
— Mark Twain
From Twain Quotes.