TacticsPlay as white

Double Bishop Mate

Two bishops on neighbouring diagonals mate a king in the corner: one checks along the long diagonal to h8, the other covers g8, and the king's own pawn on h7 blocks the last square.

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Introduction

Two bishops on adjacent diagonals control a whole corner. Against a king on h8 one bishop checks along the long diagonal and covers g7, the other covers g8, and the king's own pawn on h7 does the rest. The art is in opening the long diagonal — a check, a block, and the blocker is taken.

Lesson Content

Try this position

Two bishops can mate a king in the corner by themselves. White's bishop on d5 already covers g8. The bishop on d2 wants the long diagonal from c3 to h8: ♗︎c3+ is check, Black can only block with the rook on f6, and ♗︎xf6 is checkmate — g8 is covered by one bishop, g7 by the other, and h7 is Black's own pawn.

Mating NetKing Attack

Try this position

1. ..♗︎c3+

Put the dark-squared bishop on the diagonal that ends on h8.

♗︎c3+ checks along the long diagonal. The king cannot step to g8 — the bishop on d5 covers it — so Black must block: 1. ..♖︎f6 is the single legal reply. Then ♗︎xf6 is checkmate.

Mating NetKing Attack

Alternative Moves

♗︎xc1 — ♗︎xc1 wins a bishop, but it lets the mate slip: Black answers 1...h5 to give the king air, and with two rooks on open files and the bishop on d3 pointing at White's king it is Black who has the winning attack.

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2. ♗︎xf6#

Take the blocker — the diagonal opens again.

♗︎xf6# — Checkmate. The bishop on f6 covers g7 and h8, the bishop on d5 covers g8, and the pawn on h7 is Black's own. Two bishops, side by side, and the king has nowhere to go.

Mating NetKing Attack

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The same two diagonals, one sacrifice earlier. White's bishop on c4 covers g8. The bishop on h2 wants the long diagonal — but the knight on d7 guards e5, the square it needs. So White pays: ♕︎xf8+ takes the rook and drags the knight to f8 with 1. ..♘︎xf8, the road to e5 is open, and ♗︎e5+ ♕︎f6 ♗︎xf6 is checkmate.

Mating NetSacrificeDecoy

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3. ♕︎xf8+

Which black piece guards e5? Make it move.

♕︎xf8+ — The queen gives itself up for the rook — and for the knight's square. Black must recapture, 1. ..♘︎xf8, and the knight no longer guards e5. Now ♗︎e5+ ♕︎f6 ♗︎xf6 is checkmate.

Mating NetSacrificeDecoy

Alternative Moves

♗︎f7 — ♗︎f7 threatens nothing Black cannot meet: after 1...♔︎g7 the white king on f1, with Black's bishop on f2 and queen on b6 close by, is the one in danger — White is losing instead of mating.

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3. ..♗︎e5+

The long diagonal is open now — use it.

♗︎e5+ checks along the long diagonal. The king cannot go to g8 — the bishop on c4 covers it — so Black has to block with 1. ..♕︎f6, and ♗︎xf6 is checkmate.

Mating NetKing Attack

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4. ♗︎xf6#

Take the blocker on the long diagonal.

♗︎xf6# — Checkmate, and the queen sacrifice has paid for itself. The bishop on f6 covers g7 and h8, the bishop on c4 covers g8, and the black pawn on h7 blocks its own king: the double bishop mate.

Mating NetKing Attack

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White's bishop on f7 covers g8 and e8, and the bishop on g5 is aiming at the long diagonal — but Black's bishop on g7 sits on it. Which move starts the forced mate?

Mating NetKing Attack

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Why do two bishops on neighbouring diagonals mate a king in the corner?

Mating Net

Key Takeaways

Two bishops on adjacent diagonals control a whole corner — look for it whenever a king sits on h8 with a pawn on h7.
The long diagonal is usually blocked; a check forces the block onto a square the bishop can then capture.
Whatever guards the key square — a rook on f8, a knight on d7 — is worth a queen to remove.

Now play it through

Step through every move on a real board, try the wrong ones, and ask Knighty why they fail.

Practice Interactively

Related Lessons

Boden's Mate

Mate in Four

Deflection and Decoy

Summary

The double bishop mate: one bishop checks along the long diagonal and covers g7, the other covers g8, and the king's own pawn on h7 finishes the cage. Open the long diagonal with a check, force a block, and take the blocker.

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Next in this course

Hook Mate

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