Making my Point

In "Bishop and Knight Checkmate," I offered some mild criticism of Kevin at thechesswebsite.com. In his YouTube video teaching checkmate with bishop and knight and repeats the phrase, "it doesn't really matter," as he emphasizes general concepts. He communicates to his viewers that moves grounded in calculation or memorized patterns are less important than general concepts.

There are three steps or phases in this checkmate.

1) centralize and drive the king to the edge,
2) drive the king from wrong corner to right corner,
3) checkmate.

General principles--centralizing ones pieces and coordinating them--do prevail in the first phase, but failure to calculate runs risks. Last night, I spent a few minutes continuing my practice of this checkmate. I started from one of the exercises that I created for my series, Essential Tactics. Two books containing these exercises are available through Amazon: the eBook Essential Tactics: Building a Foundation for Chess Skill contains the exercises and solutions; the paperback Essential Tactics: The Worksheets is designed for teachers wishing to use my worksheets with their students.

White to move

The tactic here is a simple skewer that wins the Black queen by promoting the pawn to a queen or bishop. Naturally, promotion to a queen is the sensible and correct move, unless one is seeking practice checkmating with bishop and knight.

In the course of my practice, I made many moves that tablebases reveal to be the best possible. Often there are several different moves that lead to checkmate in the minimum number of moves. However, I made several moves that were short of perfection. One move added six to the number required to bring about checkmate. Two missteps of this magnitude would have awarded the computer a draw by the fifty-move rule.

Stripes,J -- Stockfish for iPad
29.05.2017

1.h8B+ Kc5 2.Bxb2 Kb4 3.Nf3 Kc5 4.Kg2 Kb4 5.Kf2 Kc5 6.Ke3 Kb4 7.Bd4 Kb5 8.Ne5 Ka6 9.Ke4 Kb7 10.Kd5 Kc7 11.Kc5

11.Nc4 is better. Why? The knight needs to prepare to move to c7 in order to evict the king from a8. The king wants to move to c6. But, perhaps these plans are getting a bit ahead of the position. Black's king is not yet on the edge. These squares are vital for the second phase; the game is still in phase one. It is not easy to determine why 11.Nc4 is best. Tablebases indicate that it is the only move leading to checkmate in 23 moves, while 11.Kc5 is one of seven options that lead to checkmate n 24 moves.

11...Kb7

White to move

12.Ng6

12.Kd6 is one of three choices that lead to checkmate one move faster than 12.Ng6. I thought that I had found a clever route to d5, where the knight can reach c7. But, again, this stage of the game is still the first step--driving the king to the edge.

12...Kc7 13.Ne7 Kd7 14.Nd5 Ke6

White to move

We see the consequences of carelessness. My efforts to prematurely play the second phase have unnecessarily extended the first. Now, I have a single move that keeps matters under control. I failed to execute it.

15.Kc6

15.Ne3 leads to checkmate in another 20 moves. With my move, I  am further from the finish of this game than I was on move 11. There is a principle of piece coordination that might have helped me to see my way through the fog: keep the knight on the same color square as the bishop.

15...Kf5 16.Nc3

16.Nf6 takes away e4 and g4 from the king. Black's king is forced to the edge after the subsequent moves 16...Kf4 17.Kd5 Kf3 18.Ke5 Kg3 19.Ke4 Kg2 20.Kf4.

16...Kg4 17.Kd5 Kf4 18.Ke6 Kg5 19.Ke5 Kg4 20.Ke4 Kg3 21.Be3 Kg2

White to move

22.Kf4

22.Ne2 forces the king to the edge, and prepares to move the knight to g3, where it evicts the king from h1. My move also forces the king to the edge. This was the correct point in phase one to think about optimal piece placement during the second phase.

22...Kh3 23.Kf3 Kh4 24.Kf4

I should have recognized the position after 24.Ne4. 24...Kh5 25.Kf4 Kg6 26.Ng5 Kg7 27.Bc5.

24...Kh3 25.Ne4 Kh2 26.Kf3 Kh1

White to move

Now, I feel that I understand what I am doing. Having extensively practiced phase two over the past few days, it has become routine.

27.Ng3+ Kh2 28.Bf2 Kh3 29.Bg1 Kh4 30.Ne4 Kh5 31.Kf4 Kg6 32.Ng5 Kg7 33.Bc5 Kf6 34.Bd6 Kg6 35.Be7 Kh5

White to move

36.Kf5

36.Nf7 is faster per the method I had learned from Bruce Pandolfini. 36...Kg6 37.Ne5+ Kh5 38.Kg3. It is good to remain flexible.

36...Kh4 37.Bd6 Kh5 38.Bg3 Kh6 39.Ne6 Kh5 40.Ng7+ Kh6 41.Kf6 Kh7 42.Kf7 Kh6 43.Bf4+ Kh7 44.Ne6 Kh8 45.Bg5 Kh7 46.Nf8+ Kh8 47.Bf6# 1–0

Checkmate with knight and bishop took me 45 moves after the last capture. I can do better. Surely, it does matter how one plays the pieces during the first phase of this checkmate. That was my criticism of Kevin. My own errors last night make my point.