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 hand is difficult, so there exist many bidding systems assigning meanings to bids, with common ones including Standard American, Acol, and 2/1 game forcing. Contrast with Spades, where players only have to bid their own hand. After the contract is decided, and the first lead is made, the declarer's partner (dummy) lays his cards face up on the table, and the declarer plays the dummy's cards as well as their own. The opposing partnership is called the , and their goal is to stop the declarer from fulfilling his contract. Once all the cards have been played, the hand is