How can the Blackwood convention help a partnership bid a slam?
Card editor of the London Field W.H. Whitfeld published this bridge problem in 1885. South is declarer and has the lead with hearts as trump. With a sophisticated finesse, South can win every trick. South begins by leading the ace of diamonds, which, depending on what the opponents discard, opens a possible finesse of North's jack of diamonds. Next, South passes the lead to North with a spade that North trumps. North then leads the last heart, and South discards the 10 of clubs. With the lead of the last trump and then the ace of clubs, the defenders are presented with an insurmountable dilemma. East must hold two diamonds or South takes the last two tricks in the suit by discarding a spade. However, in order to hold on to two diamonds, East must discard the jack of spades, which in turn would force West to hold the queen of spades. Since West also needs the queen of diamonds and the jack of clubs to avoid losing a trick, a discard from any of the three suits will allow South to win all of the remaining tricks by an appropriate discard.
The Blackwood convention is a strategic bidding method in contract bridge designed to help a partnership determine if they have the necessary high-card strength to bid and make a slam.12
By bidding four no-trump, a player asks their partner to disclose the number of aces held in their hand. The partner responds at the five-level to indicate their count:12
- Five clubs: Zero or four aces12
- Five diamonds: One ace12
- Five hearts: Two aces12
- Five spades: Three aces12
Once the ace count is established, the original bidder can further explore the hand's potential by bidding five no-trump to ask for kings. The partner then responds using a similar structure, bidding six clubs for zero kings, six diamonds for one, and so on. This systematic exchange of information allows the partnership to make an informed decision about whether to commit to a small or grand slam.12
Would you like to know more about other conventions used in slam bidding?