A lot of people have written about how to force mate with a Knight and a Bishop. While you might think that my contribution will be "just another" article on the same old stuff, consider this. I can do this mate from any non-drawn position with 00:01:00 on my clock, which is something that quite a lot of titled players can't do. The reason I can do this is that I know which squares are important to control, and when and how to control them.
Everyone knows that you have to use the King and the two pieces to drive the King into a corner that is the color of the Bishop. The hard part is to have a clear strategy to do do this.
With that in mind, let's walk through an example.
The strategy follows these steps.
1.gain control of the center.
2. drive the King to the edge of the board
3. Force the defending King into a square that is the color of the Bishop.
4. Set up and close the mating net.
Some players have the idea that once you get the defending King to the edge you have to keep it there. This isn't really true. It's better to think of confining it to a triangle formed by the Bishop, assisted by the Knight. You create the effect of parallel diagonals, and this is what confines the defending King. Once you understand this, you get an idea of which squares to control. If you understand which squares to control, then the placement of the Knight becomes easy to calculate.
Consider the position below. The Bishop is a light squared Bishop, which means that the game will end on either in the corner h1 or a8. Given what I showed in the previous example, maybe you can now figure out where the Knight should be placed. Go ahead. Look at the board and think about it for a bit. Where will the Knight go?
The first thing you should notice is that the Knight is in danger of getting trapped by the defending King. You will need the Bishop to cover b3 or c2 to preserve the Knight. Next, should should think like this. The Bishop is light squared, so the Knight will need to cover crucial dark squares. What dark squares might those be? Go back and look at the board. Think about this. Here's a clue. There are eight squares that you should be regarding. Yes, eight.
d2 e3 is one pair of dark squares, f4 g5 is another pair. They form a nice diagonal segment.
The other set of dark squares to consider is the mirror image of the first set. b4 c5 and d6 e7
Now, since you know you will have to control one of these pairs of squares with your Knight, you can easily figure out where your Knight will be headed. At this point, the defending King is free to run, so we don't yet know where the Knight goes. Once we get control of the center, things will become more clear.
Below, I play through the position we just considered, and the annotations explain the thought process.
If you are with me so far, then you have a good idea of how to think about this endgame. Take a look at this position,
Now that you have had a look at the position, name the four squares that might be the Knight's key destination. Can you do it? In the previous example, I mentioned which squares the Knight had to control. Now I am asking which squares are the Knight's destination.
The Bishop is a dark squared Bishop, so the Knight will need to cover key light squares. The future destination squares for the Knight are c5 d6 e3 f4. You don't know which one yet, because you don't know which way the defending King will try to run.
The thought process is explained in the annotations above. This time the Knight ended up being needed on e3. That was determined by which direction the defender ran.
Set up a couple of positions with a Knight and a Bishop, and study the board according to this method. If you practice that a few times, this mate will become fairly easy to perform.