White has some of the elements of Boden’s mate in place. There is the bishop’s attack on the dark square in front of Black’s king, which otherwise is trapped by his own pieces; and White has a queen ready to play QxQ, drawing the b7 pawn forward to open the other diagonal. The problem this time is that White’s own knight blocks his bishop’s path to a6. The natural idea is to vacate White's knight from b5 in a violent manner that holds the initiative—preferably a check. 1. Nd6+ is a blunder, as after 1. …BxN the White bishop’s path to b8 no longer is clear. Correct is 1. Nxa7+, which requires the reply BxN. The finale is the normal 2. QxQ+, b7xQ; Ba6#.

Notice the importance of the order of operations: if White starts with QxQ expecting to play Nxa7 next, it will be too late; for the first exchange gives Black's king a flight square when White gives check with his knight. This mate, like many others, depends on keeping the king’s range of motion under tight control, with important assistance often furnished by his own pieces as they help block the king into its position. Be careful about moves to set up mate that inadvertently give the king breathing room.