Mate in 3: knight to d6 (b5·3)
c9-22446naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Mate in 3: a forced sequence that ends in checkmate.
A fork made possible by the Chess960 piece placement.
Difficulty 1860 ShuffleRating — for advanced tacticians.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
In a mate in three every move must be forcing; the defender should never get a free tempo. Find the check or threat that herds the king, calculate the single defence to each, and confirm the net closes on the third move.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king d1, rook b1 f2, bishop d3, knight b5, pawn a2 c2 d2 h2 f3 g3 d5.
Black: king b8, rook g6 a8, bishop d8 e8, knight f5, pawn g5 h5 c7.
12 white and 9 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
White are ahead by 1 points of material (23 against 22; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on b8.
It is White to move on move 27, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 3. Files fully open (no pawns of either colour): b, e — natural highways for the rooks and queen.
Black hold the bishop pair, an edge in open lines. The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
27. Nd6+ Bb5 28. Rxb5+ Ka7 29. Rb7#
Why it works
- Great move! knight to d6 keeps the pressure (#2).
- Well found: rook to b5 (#1).
- Precise: rook to b7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Bb5, then Rxb5+ and you win the bishop.
Move by move
- 27. Nd6+ — knight to d6 with check
- Bb5 — bishop to b5
- 28. Rxb5+ — rook to b5 (capture) with check
- Ka7 — king to a7
- 29. Rb7# — rook to b7 and it is checkmate
Types in this puzzle
Mate in 3
A forced checkmate in three moves.
Mate in three is a forced staircase: each of your moves narrows the opponent's choices, and the third one ends the game. Look for the start among checks and sacrifices — quiet first moves are rare in mating problems, but deliciously sneaky. Keep the tree in your head: every defense gets its own branch. Do not stop calculating after move two — see the final mating picture with your own eyes.
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
Knight fork
One knight move attacks two targets at once — the opponent can only save one.
A fork is one move that attacks two targets at once, and no piece forks better than the knight. Look through the knight's eyes: it jumps in an L and never moves along straight lines, which is exactly why its threats get missed. Both victims of a knight fork always stand on squares of one color, while the knight strikes from the opposite color. Hunt for the square from which the knight hits the king and a heavy piece at once.
About this position
These pieces come from starting position #569.
SP-569 · BastionGuard — Off-centre king (c/f), no knight on the a- or h-file.
The king starts on c1, the rooks on a1 and g1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
The pawn on b2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 489.
The engine's main line opens with h4.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #569Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-569
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