14 January 2025

Knight and Bishop Checkmate: How and Why

Is is necessary to know a checkmate that you will never need to execute? Aside from deliberate choices due to underpromotion, I have never had to checkmate with a knight and a bishop in a game. I was on the weaker side in a blitz game on Internet Chess Club 25 years ago and got a draw because my opponent did not know how to perform the mate. I saw one young student try and fail in a youth tournament, and then in the very next round have the ending again, this time with the lone king and another draw.

In one tournament that I won, my last round opponent had failed to execute the checkmate in the previous round, else he could have won the event with a draw against me.

Many players never face it.

In Silman’s Complete Endgame Course: Beginner to Master (2007), Jeremy Silman writes:

I heretically decided not to include Bishop and Knight vs. Lone King because it’s far from easy to master, and it occurs very rarely in over-the-board play. In fact, I only got it once in my entire career, while IM John Watson and IM John Donaldson never got it at all! Is such a rarity really worth the two or three hours it would take to learn it? I say no. (xv)

On the other hand, Thomas Engqvist in 300 Most Important Chess Positions (2018) considers it of such importance that three of the 300 are concerned with this checkmate. Acknowledging its rarity (“it will probably happen once or twice in your life”), Engqvist states:

I used to teach children this endgame at a very early stage and they should know how to do it before they reach an Elo rating of 1500 to get a good feeling for how knight and bishop can harmonise together like a bishop pair. (184)

Practicing positions with few pieces develops understanding and appreciation of each piece’s unique capabilities. As Vasily Smyslov stated in Vasily Smyslov: Endgame Virtuoso (1997), "the properties and peculiarities of the pieces are most clearly revealed in the endgame" (6). Most chess study positions involve knowledge and skills that will be applied to other positions.

Yesterday, using the useful “Table of Computer Database Results for Pawnless Endings” in Karsten Müller and Frank Lamprecht, Fundamental Chess Endings (2001), I set up the knight and bishop ending that is longest distance to checkmate and played it against Stockfish. After my first five moves, I reached this position and noted the wall created on the central squares by the bishop and knight.

Black to move

I also worked through the three positions in Engqvist’s book. The first two involve the technique I have learned, forgotten, and relearned (see "Bishop and Knight Checkmate"). The third position is presented to teach the technique in lessons for beginners on Lichess that I have criticized it as more difficult.

It comes from Andre Chéron, Lehr-und Handbuch der Endspiele (1964). With Engqvist’s encouragement, I decided it was worth learning. It was not as difficult as I had thought and I spent some time practicing against the computer.

Then, I searched ChessBase Mega 2024 for endgames that reached a knight and bishop against a lone king. There are many more than I expected. Finding one that ended in a draw, I started going through the game. At several points where I thought I saw an improvement, I played from that position against Stockfish. Then, I used Stockfish and tablebases to identify areas where my play could be improved.

This exercise showed me that knowing more than one technique for executing the checkmate had practical implications. In a game, one might find one of the techniques is much faster than the other.

Here are some positions from that game. I do not know how much time pressure existed when the player was unable to finish successfully. An internet search turned up tournament information that listed the Black player’s rating as 1850.

Black to move

Black can force checkmate in 8 moves. The game went on another 20.

Nine moves earlier, Black had a mate in 9.

Black to move
A few moves prior, Black had a mate in 15, did not play it perfectly, but made progress as White did not offer the best defense.

Black to move
The closest Black came to finishing was mate in seven.

Black to move
109...Be3 (or Bf4, Bg5, Bh6) should be played, forcing White to the a-file. 110.Ka3 Kc3 111.Ka2 Bc1 and the bishop occupies the critical diagonal. 112.Kb1 Nd3 113.Ka2 Kc2 114.Ka1 Bb2+ 115.Ka2 Nb4#.

Students wanting to learn this checkmate could start with positions where checkmate can be forced in three to six moves and build from there.






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