Checkmating with two bishops: the two-diagonal net technique
King and two bishops are enough to checkmate a lone enemy king. The method resembles the queen's or the two rooks', with one extra subtlety: diagonals.
Key takeaway
Two bishops complement each other perfectly: one controls the light squares, the other the dark squares. Together, they can cover an entire corner of the board.
After learning to checkmate with king and queen, and then with two rooks, here's a third fundamental checkmating technique: king and two bishops. It requires a bit more precision than the previous two, but relies on a simple idea once you understand it.
Why you need both bishops together
A single bishop can never checkmate a lone king by itself: it only controls one color of square, so it can never watch every square around the enemy king. But two bishops, one of each color, complement each other perfectly: together they can control light and dark squares at the same time, and so cover an entire corner of the board.
The method, step by step
The general idea resembles the other mating techniques: first push the enemy king toward the edge of the board, ideally into a corner, using the two bishops placed side by side on their diagonals. Then bring your own king in to help lock down the last escape squares, until the bishops can deliver the final check while the king covers every exit.
Look at the final diagram
In the position above, everything is in place. The bishop on d5 holds the black king in check along the long a8-h1 diagonal. The white king, on b6, single-handedly locks down both a7 and b7. That leaves only b8 as a possible escape square, but it's watched by the second bishop, on g3, along the other diagonal. No escape square, no capture, no block: it's checkmate.
Did you know?
There's also a checkmate with a single bishop and a single knight, but it's considered one of the hardest to execute in all of chess: it requires pushing the enemy king into the corner matching the bishop's color, and not just any corner!
Key takeaways
- ✓A single bishop can never mate alone: you need both, one of each color
- ✓Together they can cover every square in a corner of the board
- ✓The method: push the enemy king to the edge, then into a corner, with the king's help
- ✓The final mate combines a check from one bishop with escape squares locked by the king and the other bishop
Check your understanding
Why do two bishops complement each other so well for mating?