Figure 5.1.3.7[White to move]

Black’s knight on e4 is a menace to White; an enemy knight advanced to your side of the board is a constant forking threat. White could try to chase the knight away with f2-f3, but consider more forceful offensive measures before resorting to punier threats. The knight is protected twice, by the pawn on d5 and the bishop behind it on b7. The knight also is attacked twice, by the knight on c3 and the bishop on g2. White has no cheap way to force Black to substitute a piece for the d5 pawn, but he does have a more expensive method that works: Nf4xd5. If Black recaptures BxN, then of course the outnumbered Black knight gets taken with NxN or BxN and White has gained a pawn. (If Black instead recaptures QxN, White plays Nc3xQ.) Black’s other option is to take his doomed knight and attack with it, playing NxN. Then White plays Nd5xN, still up a pawn and now in control of the center.

The immediate point of the position is that even where one of the guardians of an enemy piece is a pawn, removing it with a sacrifice still may enable you to make small material gains—and to improve your position or weaken your opponent’s. The broader point is that when there are pieces or pawns in the middle of the board, they frequently will have multiple guards and attackers. When you see such tensions, do not lightly conclude that the pressures on both sides are evenly balanced; a capture of one of the defenders, even a defender that is itself defended, may tip the pressures on the contested square in your favor.