One such bonus was a ten-to-one payout if the player's hand consisted of the ace of spades and a black jack (either the jack of clubs or the jack of spades). This hand was called a "blackjack", and the name stuck even after the ten-to-one bonus was withdrawn.
Photo courtesy Kathy Quigley The Black Jack Battlefield is the site of the Battle of Black Jack, in which a Free-State militia led by the abolitionist John Brown attacked and defeated a pro-slavery militia on June 2, 1856.