Mate in 3: queen to d5 (c4)
c9-27123naming 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 d2, queen c4, knight a2 f3, pawn b2 h3.
Black: king h5, rook d5, pawn f6 h6 a7 b7.
6 white and 6 black pieces are on the board; the puzzle position arises after move 40.
The position in numbers
White are ahead by 8 points of material (17 against 9; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d2, the black king on h5.
It is White to move on move 40, with 10 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 2 pawns, Black 4. Files fully open (no pawns of either colour): c, d, e, g — natural highways for the rooks and queen. Half-open for White: a, f.
The White king has 6 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
40. Qxd5+ Kg6 41. Qg8+ Kf5 42. Qg4#
Why it works
- Best move. queen to d5 is exactly what the engine plays (#2).
- Spot on — queen to g8 (#1).
- Precise: queen to g4 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kg6, then Qg8+ and you win the rook.
Move by move
- 40. Qxd5+ — queen to d5 (capture) with check
- Kg6 — king to g6
- 41. Qg8+ — queen to g8 with check
- Kf5 — king to f5
- 42. Qg4# — queen to g4 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.
About this position
These pieces come from starting position #639.
SP-639 · BastionGuard — King shifted to c or f, knights kept clear of the edges — 168 positions in all.
The king starts on c1, the rooks on a1 and e1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
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 224.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #639Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-639
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