In Harmony

I wrote in my last blog entry that while guessing Morphy games, I also spent some time learning simple (in terms of the number of pieces) endgames, like king and pawn endgames and minor piece endgames.

I only have had the bishop-and-knight mate once (never on the defending side), but it came just after I turned 7 years old! Amusingly, as that was one of the checkmates that Richard Shorman had taught me, I had some sense of what to do.

I was white against Edmund Rendler, both of us probably around 1100-rated players (my first USCF rating was 1000), and it was played at the Koltanowski (Kolty) Chess Club in Campbell, CA on July 18, 1991.

(FEN: 8/8/1N2k3/8/4KB2/8/8/8 w - - 0 90)

Actually, there was no reason for it to even get here. I had won a couple pieces in the middlegame, but instead of exchanging all the pieces and leaving just my extra material and pawns, I traded all the extra material and pawns, leaving myself with just the bishop and knight.

Anyways, the first step is to make sure Black’s king is driven to the dark-square corner. We had already started the B+N endgame a few moves ago, and I had put my knight on b6 and bishop on f4 to flush Black’s king out from the queenside.

So I continued with 90.Bc7, and after 90…Kf6 91.Kf4 Ke6, I continued with 92.Kg5. The bishop and knight work in perfect harmony, covering each other’s weaknesses and hemming Black’s king in. White’s king slowly draws the noose tight.

(FEN: 8/2B5/1N2k3/6K1/8/8/8/8 b - - 0 92)

The game continued 92…Kf7 93.Kf5 Ke7 94.Ke5 Kf7 95.Bd8 Ke8 96.Bg5. Once again, the bishop and knight prevent Black’s king from escaping, but now the net on the kingside is closing.

Richard Shorman taught me that the key positions were one of the following two “four-square positions”:

That’s what I was already aiming for with the bishop on g5. After 96.Bg5, Rendler played 96…Kf7 and the game continued 97.Kf5 Ke8 98.Ke6 Kf8, reaching the position in the diagram below:

(FEN: 5k2/8/1N2K3/6B1/8/8/8/8 w - - 0 99)

So the key is to get the knight to the e5-square, and then the bishop and king on some combination of e7 and g5. In that case, the three pieces work together perfectly to force Black to the corner in the shortest amount of time possible.

Now that the king covers the d7-square, the knight is no longer needed on b6. Thankfully, after 99.Nc4 Kg7 100.Ne5, the knight is just in time to cover the g6-square. Now the Ne5 and Bg5 serve to make sure the king can’t step forward, and after 100…Kf8 101.Kd7, the White king makes sure the Black king has only one direction to run. After 101…Kg7 102.Ke7, we’ve reached one of the key “four-square positions” above.

(FEN: 8/4K1k1/8/4N1B1/8/8/8/8 b - - 0 102)

The game finished 102…Kg8 (note that if it’s White to move here, he can lose a move with Ke8 or Bf4, for example and then the rest is the same) 103.Bh6 Kh7 104.Bf8 Kg8 105.Nd7 Kh8 106.Kf7 Kh7 107.Nf6+ Kh8 108.Bg8#.

My one and only real-game experience with the bishop and knight checkmate. It’s kind of amazing that GM Epishin, a long-time Karpov second and a strong GM in his own right, was unable to win this endgame in 2001. He must’ve only had 30 seconds without an increment at the start of the endgame. Looking at the entry on Wikipedia, apparently this endgame comes up about once every 5000 games. Good thing I learned how these pieces work together early on …

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