Figure[White to move]

What does White attack? Black’s rook, which he could take with his king if it weren't protected by the pawn on f7. So turn your attention to the pawn: what can you do to it? Capture it: Bxf7. Of course Black recaptures KxB, but White has made the rook much more vulnerable by converting its guard from a sturdy pawn into an easily frightened king. Now it’s a matter of driving off the king with checks by White's queen—and remember that it may take more than one check to accomplish the purpose. White starts with Qd7+. Black resists the invitation to abandon the rook, and so plays Kf6. Now White adds another check: Qd6+. Black has to move his king to f7 or g7. Now notice that while Black’s king still protects the rook, White’s queen now attacks the rook a second time. White plays QxR+ and Black is unable to recapture because White’s queen has protection from its king.

The position is a fitting conclusion to this subsection because it involves several of the ideas we have considered here. First an exchange is performed so that a piece White attacks ends up protected only by its king. Then two checks are used to manipulate the king’s position. Finally, the same piece that administers the checks also is used to take the target.