Mate in 3: queen to a4 (d4)
c9-27925naming 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.
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.
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 a2, queen d4, rook e7, bishop f4, knight f2 g2, pawn h2 a3 g3.
Black: king a6, queen h6, rook g7, bishop f7, pawn d5 f6 b7.
9 white and 7 black pieces are on the board; the puzzle position arises after move 31.
The position in numbers
White are ahead by 6 points of material (26 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 a2, the black king on a6.
It is White to move on move 31, with 54 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 3. Files fully open (no pawns of either colour): c, e — natural highways for the rooks and queen. Half-open for White: b, d, f.
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
31. Qa4+ Kb6 32. Bc7+ Kc5 33. Nd3#
Why it works
- Best move. queen to a4 is exactly what the engine plays (#2).
- Spot on — bishop to c7 (#1).
- Precise: knight to d3 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kb6, then Bc7+ and you stay on top.
Move by move
- 31. Qa4+ — queen to a4 with check
- Kb6 — king to b6
- 32. Bc7+ — bishop to c7 with check
- Kc5 — king to c5
- 33. Nd3# — knight to d3 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.
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 #760.
SP-760 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
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 b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 397.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 2 of 100 — class D — largest edge. Engine evaluation of the starting position: +61 centipawns for White (depth 46, 400 000 000 nodes).
In 50 self-play games White scored 56.0% (95% CI 42.3–68.8%).
Explore position #760Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-760
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