Most of the positions just reviewed involved targets that were protected only once. Their guardians may have had guardians, creating lines of protection that had to be traced out; but even then there usually was just one such line of protection to worry about. Often, of course, a piece will be protected two or three times—in other words, with two or three chains of guards, short or long, that prevent it from being taken. The logic involved in removing the guard doesn't change much in those cases, but a new wrinkle or two can appear in the resulting patterns. And seeing the tactical opportunities latent in such positions takes a little practice, because to the untrained eye a piece protected two or three times will not seem vulnerable at all. Yet perhaps it is. And liquidating a position where there are multiple guards on each side also may shake up the board sufficiently to permit a fresh and unexpected tactical blow—a fork or pin or discovery—during the sequence or at the end of it.
In the study to the left you are playing the Black pieces; your bishop is loose and is threatened by White’s queen. A lesser player would move the bishop or add protection to it, but you, the seasoned student of sharp play, step back to inspect your offensive options, starting with a look at what threats you currently make. Your rook attacks the bishop on g2—which is protected by White’s king. Your queen and bishop attack the knight on e4—which is protected twice, by White’s bishop and queen. A natural idea would be to take out one of the knight’s guards with a capture: RxB+, sacrificing the exchange to gain a piece next move. Since the move is a check, it leaves White no time to reply QxB; he must recapture with KxR. Now the knight on e4 is guarded only once and attacked twice. Better still, either capture of it—with your bishop or queen—then forks White’s king and rook on b1. (Observe the triangle.)
But which way of taking White’s knight is best? If you use your bishop, then White moves his king and you win back the exchange with BxR. If Black instead takes the knight with his queen, play might go 3. Kh2, QxQ+ (a discovered attack against the b1 rook); 4. e3xQ, BxRb1; 5. RxB. (Or 3. QxQ, BxQ+; 4. Kf2, BxR; RxB.) The final gain in material is the same in all these variations: you end up a whole piece ahead. The difference is that starting with 2. QxN also ends up eliminating both queens from the board. This is good for familiar reasons. The fewer the pieces left on the board, the more significant your advantage becomes and the harder it is for your opponent to climb back into the game. So a sequence that gets both queens off the board as well as winning a piece generally is better than one that wins a piece without more.