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
Contract bridge to make a game (nine tricks at notrump, ten tricks in hearts or spades, 11 tricks in clubs or diamonds), which yields bonus points if bid and made. East-West are "competing" in spades, hoping to play a contract in spades at a low level. 4 is the final contract, 10 tricks being required for N-S to make with hearts as trump. South is the "declarer", having been first to bid hearts, and the player to South's left, West, has to choose the first card in the play, known as the "opening lead". West chooses the spade king because spades is