Grand slam force Grand slam force The Grand Slam Force is a bidding convention in contract bridge that was developed by Ely Culbertson in 1936. It is intended to be used in cases where the combined hands of a partnership are so strong that a slam (winning at least 12 tricks) is a near-certainty and a grand slam (winning all 13 tricks) is a possibility. It allows one partner to gain information on the quality of trumps in the other partner's hand. When this convention is in force, a bid of 5NT (five notrump), when it does not conflict with other conventions used
Bridge convention Bridge convention Contract bridge is a trick-taking card game played by four players in two competing partnerships in which a sequence of , also known as the auction, precedes the play of the cards. The purpose of this bidding is for players to inform their partners of the content of their hand and to arrive at a suitable contract at which to play the hand (or to prevent the opponents from arriving at a suitable contract). Although bidding is often "natural" (describing a hand by simple reference to possession, shape, and strength of the named suit) players may also bid