While the Declarer tries to preserve or find Entries, the Defense
acts as Bridge terrorists - they try to destroy Entries. Sometimes 
at all costs. This is done in the suicide play (Deschapelles Coup) 
where one or two tricks are sacrificed in when blowing up an Entry. 
Before we look at these extreme measures, let's examine some of 
the more conventional weapons used by the Defense. 

The Hold Up
The Declarer is not the only one at the Bridge table who can
the Hold Up weapon. The Defenders can also use it
with deadly accuracy. 
In example 1. you are sitting behind Dummy. Declarer led the 4 Cand your partner played the 8 C.  Either your partner is giving you a count by playing high / low to show an even number of cards in the 
suit, or he has a singleton.  What ever the reason you know that Declarer has at least one more Club. And if you win the first Club trick with you Ace, then Declarer has a clear road to Dummy and the rest of the good Clubs. So the strategy here is not to win the first Club trick but instead Hold Up. Declarer plays the 6 C and your partner completes his signal with the 2 C. Since there are no more Clubs out you win this trick. Declarer does not have another Club to get to Dummy; the road to Dummy is blocked. If you partner did not play a Club on the second round it would mean that the Declarer started with 3 cards in that suit, and you would have to Hold Up one more round.



S4 2
CK Q J 10 9 7

 S 9 7 6 5 3
 C A 5 3

In example 2. Declarer leads the 4 D and partner plays the 2 D. If partner's Diamond is a singleton then Declarer has three cards in that suit. Holding up on round in Diamonds is essential, but Declarer can prevail by continuing to play Diamonds driving out both your honors and getting to Dummy with the A H. What to do? Surrender ? No. Attack, attack, attack! Attack the A H. After winning the first Club trick lead a Heart and try to drive out Dummy's H

H  A 6 2 
D  Q J 10 9 7 5
C  7 5
 H 9 7 6 5 3
 D A  K 3
 C J 10



S 7 4
H A 6 
D K Q J 108 7 2
C 9 3 2

S Q 10 6 3 2
H 10 8 5
D 5
C Q 6 5 4

S A 8 5
H K 9 4 2
D A 6 3
C 10 8 7

S K J 9
H Q J 7 3
D J 9 4

The bidding in example 1 above, is fairly automatic; 1 NT ===> 3 NT.
West's opening lead is the 3 S. East wins with the Ace and goes into
the tank. If partner had the King Queen Jack (or even the 10), he would
have led the K S. Therefore Declarer has a Spade stopper. Once my A D is knocked out there will be 6 tricks in Dummy, a Spade and 5 Diamonds; and most likely 2 Clubs (or a Club and a Heart ) in the closed hand. That's 9 tricks and the contract. Must keep Declarer from running those Diamonds. But how?
Hold up with the A D. But that seems a bit futile since the A H is the
entry to Dummy. Solution: blow up the A H. The weapon of mass
destruction, known as Deschappelles Coup, will deployed by leading the K H at trick 2. That lead will give the Declarer the Queen and Jack of Hearts, but will keep Declarer from making 5 Diamond tricks. Note: if Declarer holds up with the A H, East continues the suit knocking out the Ace in Dummy. If South wins the first Heart lead, then East will hold up  and win the third Diamond lead, isolating Dummy forever. Declarer will only make 1 Spade, 3 Hearts, 2 Diamonds and 2 Clubs; 8 tricks for down one.