Figure 3.2.6.3[White to move]

Start by noticing the same rough starting pattern here as in the previous position: White has vertical pressure against g7 and a bishop pointed at the same square. He can give check and form the kernel of a discovery by capturing there with a heavy piece. This time White can’t just take the pawn on g7 and start rolling; the pawn is guarded by the knight on f5. But White has a piece he can sacrifice to the cause: his queen. So 1. Qxg7, NxQ and now the pattern here more precisely resembles the previous one. White plays RxN+, accomplishing two things: the move checks the king, forcing it onto its only flight square—h8; and it sets the pattern for a discovered check by moving White’s rook into his bishop’s path and forcing Black’s king onto the same diagonal. A windmill is in place. If White moves his rook, the king will be in check and move back to g8; then if White brings his rook back to g7, the king will be in check again and will move back to h8.

How to exploit this? White first explores the usual destructive options on the seventh rank with RxB+, discovering check. Black plays Kg8; White plays Rg7+; Black plays Kh8, and the pattern is reset. After White has taken both Black pawns on the seventh rank, White will use the two rook moves made possible by his discovered check not to return to g7 but to reach Black’s queen, just as in the previous problem: he plays Rb7+; Black plays the compulsory Kg8; and now White plays RxQ. White nets two pieces and three pawns with the sequence.