Mate in 3: queen to a6 (a5)
c9-21946naming 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 c1, queen a5, rook b1 h1, bishop f2 c6, knight d5, pawn a2 c2 g2 c4 e5 h5.
Black: king c8, queen g8, rook b8 h8, bishop c5 f7, knight e6, pawn d4 f6 a7 g7 h7.
13 white and 12 black pieces are on the board; the puzzle position arises after move 22.
The position in numbers
White are ahead by 1 points of material (34 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 22, with 58 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): b — natural highways for the rooks and queen. Half-open for White: d, f.
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
22. Qa6+ Rb7 23. Qxb7+ Kd8 24. Qd7#
Why it works
- Best move. queen to a6 is exactly what the engine plays (#2).
- Spot on — queen to b7 (#1).
- Precise: queen to d7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Rb7, then Qxb7+ and you win the rook.
Move by move
- 22. Qa6+ — queen to a6 with check
- Rb7 — rook to b7
- 23. Qxb7+ — queen to b7 (capture) with check
- Kd8 — king to d8
- 24. Qd7# — queen to d7 and it is checkmate
Types in this puzzle
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
About this position
These pieces come from starting position #553.
SP-553 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on c1, the rooks on a1 and h1, the queen on g1.
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 505.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 72 of 100 — class B — balanced. Engine evaluation of the starting position: +20 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #553Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-553
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