Figure[White to move]

Consolidating Excess Enemy Pieces.

In some respects this position resembles others we have seen recently, but notice that White’s position is more vulnerable. Black threatens Qf2# and at first blush White seems to have no good defense against it. Again, though, Black's king is on the g-file with a pawn and queen spread apart in front of it; again White would be able to pin the queen, and with good protection, by playing Rg1 if the pawn on g7 weren’t in the way. This time the pawn can’t be moved by taking something it guards because it doesn’t guard anything. The situation calls for a different approach: perhaps the pawn can be captured. This won't help if the piece you use to make the capture is left on the needed file, for then you would have replaced one obstruction with another. But the result may be a useful simplification if your piece will be recaptured by the enemy.

The point: White plays Rxg7+, taking the pawn and also forking Black’s king and queen. The priority of check requires Black to deal with this rather than delivering mate on f2; he has to capture White’s rook with KxR or QxR. Either way the three Black men on the g-file have been reduced to two. Now Rg1 pins Black’s queen. Black plays QxR and allows his queen to be recaptured, and in the end White has traded two rooks for a queen and a pawn. More to the point, he has turned a lost position into a winning one.

This section is titled "consolidating enemy pieces" because that is one way of looking at what happens: enemy pieces spread over multiple squares are, through captures, consolidated down to a single square, which then becomes a suitable target for a pin.