Mate in 3: queen to b8 (b2)
c9-23523naming 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 1630 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 g1, queen b2, rook b1 f7, knight h1 e5, pawn a2 d2 h2 e3 g3 c4 g6.
Black: king d8, queen a6, rook c7 g8, knight e8, pawn g4 h4 c5 e6 a7 d7.
13 white and 11 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 4 points of material (32 against 28; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on d8.
It is White to move on move 21, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. Files fully open (no pawns of either colour): b, f — natural highways for the rooks and queen.
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
21. Qb8+ Qc8 22. Rxd7+ Rxd7 23. Nc6#
Why it works
- Great move! queen to b8 keeps the pressure (#2).
- Well found: rook to d7 (#1).
- Strong! knight to c6 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Qc8, then Rxd7+ and you stay on top.
Move by move
- 21. Qb8+ — queen to b8 with check
- Qc8 — queen to c8
- 22. Rxd7+ — rook to d7 (capture) with check
- Rxd7 — rook to d7 (capture)
- 23. Nc6# — knight to c6 and it is checkmate
Types in this puzzle
Knight mate
The knight lands the killing blow from its unique angle.
In a knight mate the final blow comes from the knight — the only piece whose check can never be blocked. That makes it lethal against a cramped king: only a king move or capturing the knight itself can help. The sign: the squares around the king are occupied or covered, and there is a hop from which the knight checks while staying untouchable. Bring the knight over early — it is slower than the long-range pieces, but its strike cannot be parried.
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.
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.
About this position
These pieces come from starting position #577.
SP-577 · BastionScout — A c- or f-file king with at least one knight out on the edge.
The king starts on f1, the rooks on c1 and g1, the queen on b1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: d2, h2.
The setup belongs to the BastionScout family; read right to left it becomes position 283.
The engine's main line opens with b4.
Morozov Balance Index: 89 of 100 — class A — most balanced. Engine evaluation of the starting position: +14 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #577Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-577
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