Figure[White to move]

White’s winning sequence here ties together our present theme with the forks and discoveries studied earlier. We will spend two frames on it. White is confronted with serious trouble: a threat of mate on h2. The best defense is a good offense; he wants to go after Black’s king. When you undertake such an attack you want to be conscious of nearby mating patterns, but also of any other patterns nearby—such as possible forks that might become possible if the king moves. Those thoughts run in the background while you experiment with a check: Re8+. Black has two possible replies: Kh7 or the interposition Bf8. Kh7 puts the king in line with the loose rook on c2, and so allows White to win the rook with the fork Qd3+. It's an easy point if you remember to notice any loose pieces on the board.

That actually is Black’s best option. To see why, let’s assume Black instead plays 1. ...Bf8. Now White continues with his checks: RxB+. Again Black must choose, this time between moving his king to h7 or g7 or playing KxR:

(a) If he plays Kg7, White can start an attack that eventually leads to mate with Ne8+; but since that is hard to see, you might instead just observe that White can play the fork Rxf7+, where his rook attacks Black’s king and queen with protection from the knight on d6. Black has to play QxR, then lose his queen to NxQ.

(b) If Black instead replies to RxB+ with Kh7, White again has the fork Rxf7+ (or, again, a longer forced mate, but we are focusing for now on forks).

(c) So assume Black instead replies to RxB+ with KxR, and read on....