Who said the best offense is a good defense?

Google suggests that it is a misquote of Carl von Clausewitz, who said "The best defense is a good offense". Here's the reference: http://www.quote-db.com/index.php/quote/3717 The quote "The best defense is a good offense" has also been attributed to the heavyweight prizefighter Jack Dempsey, here: http://www.poynter.org/column.asp?id=32&aid=32072 offense to attack and defense is to protect your self against attack?"