It’s one of the trickier mating patterns to figure out as an amateur player, but it’s a useful skill to have and it reminds you of the power of the bishop pair at any point in the game.
Also, it does come up in practical play sometimes and it would be super embarrassing to drop half a point because of this!
To figure out how to checkmate with two bishops, first you need to know what the ending position is. The enemy king has to be forced into a corner, with one bishop checking them and the second one laser-beaming away their route of escape in one direction. Meanwhile, the king takes care of the rest.
It should look something like this:
You can work backwards from here to engineer the solution, but if you’re not into brain-teasers, here’s a step-by-step guide. Just like with rooks, two bishops can effectively cut off a king in one direction, but they cannot force it down to the side of the board by themselves.
You will need your own king to assist. Place your bishops next to one another to form the barrier of doom, then march your monarch next to them to force the opponent back.
This should serve you well until you reach the back rank.
Now you need to force your opponent’s king into the corner square.
Since you have both bishops at your disposal, either corner will work. (This is not the case when you’re trying to checkmate with a bishop and a knight!) By shuffling a bishop around with your king, you can slowly accomplish this goal.
First, step back with the bishop and occupy the vacant square with your king. Next, you spend two moves to move your bishop over to the other side of your second bishop, closing in the cage. Now the opponent has to move one square closer to the corner. Rinse and repeat the process until your king is just three squares away from the edge of the board and the enemy is just one step away from being well and truly cornered.
Now, it’s time for the final trick: you no longer have to swing the bishop around. Instead, move the bishop meant to deliver the checkmate to cut off the enemy’s escape route, then move your king to its final destination. Be mindful of stalemate traps! When done right, the enemy has nothing better to do than to move back and forth between just two squares. You can then give up a tempo with either of your bishops and deliver checkmate!
If you make a mistake, don’t panic: there is no way to lose the game and you have 50 moves (as per the 50-move rule) to complete the job.
Force the king back in the corner and try again!