Mate in 3: queen to a8 (a7·6)
c9-27735naming 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 1760 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 g2, queen a7, rook c1 d1, bishop b1, knight h1 c3, pawn a2 b3 e3 h3 h4.
Black: king c6, rook d8 h8, bishop b8, pawn c4 c5 f5 g5 b6 d7 h7.
12 white and 11 black pieces are on the board; the puzzle position arises after move 24.
The position in numbers
White are ahead by 13 points of material (33 against 20; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g2, the black king on c6.
It is White to move on move 24, with 42 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: c, d, f, g.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
24. Qa8+ Kc7 25. Nb5+ Kc8 26. Qa6#
Why it works
- Best move. queen to a8 is exactly what the engine plays (#2).
- Spot on — knight to b5 (#1).
- Precise: queen to a6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kc7, then Nb5+ and you stay on top.
Move by move
- 24. Qa8+ — queen to a8 with check
- Kc7 — king to c7
- 25. Nb5+ — knight to b5 with check
- Kc8 — king to c8
- 26. Qa6# — queen to a6 and it is checkmate
Types in this puzzle
Epaulette mate
The king's own pieces flank it like epaulettes — mate comes head-on.
In the epaulette mate the king stands between two of its own pieces — most often rooks — like an officer wearing epaulettes. The side squares are blocked by friends, there is no retreat, and the queen mates head-on from directly in front of the king. The sign: a king on the edge rank with both neighboring squares on that rank occupied by its own pieces. Remember, extra defenders crowding the king can be deadlier than no defenders at all.
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 #608.
SP-608 · BastionScout — The king starts one file off-centre, on c or f, and a knight begins in a corner.
The king starts on f1, the rooks on c1 and g1, the queen on e1.
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.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionScout family; read right to left it becomes position 255.
The engine's main line opens with c4.
Morozov Balance Index: 2 of 100 — class D — largest edge. Engine evaluation of the starting position: +53 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #608Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-608
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