White to move. How should white proceed?
Hey, Yancey! I read Don Sioux’s comments on Facebook
Or all put together because the formatting on this site sucks:
1.Kb6! Nh4 2.Nh6! Bxh6 3.h8(=N)! Qg8 4.Nf7+! Qxf7 5.b4! any move 6.bxc5#
I think the right line is 1.Kb6- this preserves the same knight mating threats on the kingside as would a move like 1.Kb7, but also has the threat of b4 followed by bxc5 mate. The main point is that this additional threat on the queenside means that the bishop on c1 is overloaded- it can't both play to a3 guarding the rook on c5 and take the knight when it comes to h6 to threaten Nf7#. The longest defense I can find for black is....
This threatens 2.Nf5#, so black must either play the queen to guard the f5 square, or he must take the knight on h4:
1............Nh4 (or Qf2 2.Nh6! Bh6 3.Nf5 Qf5 4.b4 followed by mate) 2.Nh6!
Now threatening Nf7#. Again, black must play the queen to guard the f7 square or take the knight with the bishop, but on 2....Qg6/g7, white will underpromote the h-pawn to a knight doubling the attack on the f7 square, overloading the queen which will then require Bxh6 anyway which then leaves b4 and bxc5# unstoppable:
Again threatening Nf7# which can only be stopped by the queen- this means black also can't guard the rook on c5 by playing d3 opening the line for the queen.....
Black's last line of defense is the check from b8 with the queen, but now white forces the queen off the 8th rank......
4.Nf7! Qf7 5.b4 followed by mate on the next move.