C&C Chess Club

Mate with bishop and knight — the right corner

White wins White to move · Basic mates · Difficulty about Elo 1800

Position: 2k5/8/2K5/8/3BN3/8/8/8 w - - 0 1
White to move · FEN 2k5/8/2K5/8/3BN3/8/8/8 w - - 0 1

The plan

The hardest basic mate — and the most important lesson about it: mate is possible ONLY in the corner of THE BISHOP'S COLOUR (here: dark-squared bishop, so a1 or h8). The defender therefore always flees to the wrong corner; from there it has to be driven to the right one along the edge using the knight's famous W-MANOEUVRE. All three pieces work as a chain: the king takes the squares in front, bishop and knight take turns providing the block. In a real game, keep the fifty-move rule in mind — from the middle of the board even perfect play takes more than thirty moves.

Why this level: Notoriously hard, 34 half-moves, brushes against the fifty-move rule

The solution, move by move

  1. 1. Be5 The dark-squared bishop controls the dark squares — mate is only possible on a1 or h8. Black therefore heads for the WRONG corner, a8.
  2. 1… Kd8 The only legal move — and it stays that way almost to the end: in fourteen of its seventeen moves, Black has exactly one square. You do not win this mate against an opponent, you carry it out.
  3. 2. Bd6
  4. 2… Kc8
  5. 3. Nc3
  6. 3… Kd8 Again with no choice. The division of labour is always the same: the bishop covers the dark squares from a distance, the king stands in front of the light ones. Exactly one square is left over.
  7. 4. Nd5
  8. 4… Kc8
  9. 5. Nb6+ The knight bolts a8: Black can no longer reach the wrong corner. Now the journey to the right one begins.
  10. 5… Kd8 The check has shrunk the cage, not driven the king away — the difference matters. The wrong corner is now closed for good.
  11. 6. Kd5
  12. 6… Ke8 The march along the back rank begins. Black is not running away, it is being driven, towards the corner that matches the bishop's colour.
  13. 7. Ke6
  14. 7… Kd8 Back, because forward no longer works. This is the rhythm of this mating technique: the defender shuttles between two squares while the blockade moves one square closer with every shuttle.
  15. 8. Be5 The chain is set: the king takes the squares in front, the bishop bars the retreat squares — Black is pushed along the back rank towards h8.
  16. 8… Ke8 And back again. Whoever loses patience here and rushes the king forward gives the opponent a second square — and starts over.
  17. 9. Bf6
  18. 9… Kf8 Past the middle of the back rank. From here on there is only one direction; there is no way back to the wrong corner any more.
  19. 10. Nc4
  20. 10… Ke8
  21. 11. Nd6+ The famous W-MANOEUVRE: the knight traces a W on the board with b6-c4-d6-f5-h6, and every one of its checks pushes the king a step further.
  22. 11… Kf8 The second check of the W-manoeuvre has worked: the king stands one square further right than before, and the knight only needed one jump for it.
  23. 12. Kf5
  24. 12… Kg8 Another half-dozen moves. The king is now two squares from the mating corner and will get there too — there is nothing else on offer.
  25. 13. Kg6
  26. 13… Kf8 The last shuttle step before the corner. The bishop is about to switch diagonals, and after that this escape square is gone too.
  27. 14. Bh4
    Sideline 14. Kh7 STALEMATE in the middle of the W-manoeuvre. The knight covers e8 and f7, the bishop covers e7 — and with this move the king takes g7 and g8. This is why you wait with the BISHOP here, not with the king.
  28. 14… Kg8 The second-to-last stop. From here only one square leads further, and it is the right corner.
  29. 15. Be7
  30. 15… Kh8 In the corner for the first time — and it is the dark one, the bishop's colour. In the light corner the very same position would be a dead draw.
  31. 16. Nf5
  32. 16… Kg8 The king has to come out once more. This is exactly where the greatest danger of this mating technique lies: if White takes away this square too, it is STALEMATE instead of mate. The attacker must leave it exactly one square right up to the last move.
  33. 17. Nh6+ The knight takes g8 — the king has only the mating corner left.
  34. 17… Kh8 And back into the corner, this time with no way out. All three pieces are in position.
  35. 18. Bf6# Mate in the corner of the bishop's colour. King, bishop and knight: none of the three can be spared.
    Sideline 18. Bd8 STALEMATE on what should be the mating move. Mate is only possible via the diagonal to h8; any other bishop move ends the game in a draw — after thirty moves of work. This is why this endgame is considered the hardest.

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