ChessBoden's mate is when the diagonals of two bishops cross right on the king: one bishop gives check, the other cuts off the king's escape. It shows up most often after queenside castling (king on c8 or c1), when d7 and d8 next to the king are blocked by its own pieces. One story says it's named after the 19th-century English player Samuel Boden, who reached this shape with a beautiful queen sacrifice in one of his games. When you play chess vs the computer and see that your opponent has castled queenside and the b-pawn is gone, think of this one.
The pattern
The black king is on c8. The squares around it:
- b7: controlled by the bishop on a6 (that's the checking line).
- b8, c7: controlled by the bishop on f4.
- d8, d7: its own rook and knight.
Black can't block on b7 and can't take the bishop on a6. The two bishops' diagonals form an X that crosses right on the black king and pins it in place.
How it happens in real games
In a real game b7 usually holds a pawn, and the bishop on a6 has no line to give check. The most common trick is: sacrifice the queen first to lure the b-pawn away and open the b7 line.
Step by step:
- The white queen takes on c6 with check. The black king can't go to b8 (covered by the bishop on f4), and nothing can block, so the b7 pawn has to take the queen.
- Once the b-pawn leaves b7, the a6-c8 diagonal is open.
- The bishop on e2 goes to a6 with check, the other bishop on f4 still covers b8 and c7, and it's mate.
White gives up a queen and finishes the game with just two bishops. Boden's famous game is said to have gone the same way: a queen sacrifice first, then mate with the two bishops.
How to avoid it
- After castling queenside, watch the diagonal in front of your b-pawn. If the b-pawn is traded or lured away, b7 (b2 for White) becomes a highway for enemy bishops.
- Don't let d7 and d8 both get packed with your own pieces. Leave your king at least one square to move to.
- Watch the enemy's two bishops. If one is aimed at your c7 and b8, and the other can jump to a6, that's a warning sign.
- When your opponent offers his queen for one of your pieces, look at what happens after you take. When the capturing pawn leaves its square, which line opens?
Practice puzzles
Show answer
1. Ba6# The bishop on d3 goes to a6 with check, controlling b7. The bishop on e5 stays put, covering c7 and b8. d7 and d8 hold Black's own pieces. Checkmate.
Show answer
1... Ba3# The black bishop goes to a3 and gives check along a3-b2-c1. The bishop on f5 covers b1 and c2, and d1 and d2 hold White's own rook and knight. Checkmate.
Show answer
1... Qxc3+ 2. bxc3 Ba3# The black queen takes the knight on c3 with check, and White has to take back with the b-pawn. Now b2 is empty, and the black bishop goes to a3 for mate, with the bishop on f5 covering b1 and c2.
FAQ
Does Boden's mate only happen after queenside castling?
That's when it's most common, because with the king on c8 (c1), d7 and d8 are often blocked by its own rook and other pieces. But anywhere the squares around the king are sealed by two crossing diagonals and its own pieces, it can happen.
Why does it take two bishops?
One bishop can only control squares of one color. The squares around the king come in both dark and light, so you need two bishops, one for the dark squares and one for the light, to seal them all.
Do you always have to sacrifice the queen first?
No. If b7 is already empty, the bishop just goes there for mate. The queen sacrifice is only there to lure away the b-pawn that's in the way.
Try it yourself
Boden's mate shows you how strong two bishops are together. Go back to checkmate patterns for the other two-piece mates, or review the castling rules to see the difference between castling queenside and kingside. When you're ready, play some online chess for free, and keep an eye on the b-pawn after your opponent castles queenside.