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
Boston (card game) in a contract to win at least eight tricks between them. The higher bid of Independence offers to win at least eight tricks playing solo. In either way, there is an extra bonus for winning all thirteen tricks formerly called "la vole", but now "le chelem", from English "Slam". All bids are solo, the lowest being to take four tricks in any suit. Each may be over-called by bidding higher number of tricks, or the same number in a better suit. For this purpose a better suit is that of Preference, previously determined by turning the last card of the