Mate in 3: pawn to c6 (b5·2)
c9-28225naming 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 h1, queen f8, rook b1 d1, bishop a3, knight d5, pawn h2 f3 e4 b5.
Black: king b7, rook a8, knight g2 g8, pawn d2 g5 c6 f6 d7 h7.
10 white and 10 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
White are ahead by 12 points of material (29 against 17; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on h1, the black king on b7.
It is White to move on move 28, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 6. Files fully open (no pawns of either colour): a — natural highways for the rooks and queen. Half-open for White: c, d, g.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
28. bxc6+ Ka7 29. Qc5+ Ka6 30. Qb6#
Why it works
- Best move. pawn to c6 is exactly what the engine plays (#2).
- Spot on — queen to c5 (#1).
- Precise: queen to b6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka7, then Qc5+ and you stay on top.
Move by move
- 28. bxc6+ — pawn to c6 (capture) with check
- Ka7 — king to a7
- 29. Qc5+ — queen to c5 with check
- Ka6 — king to a6
- 30. Qb6# — queen to b6 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.
Discovered attack
A piece steps aside and opens a second attack from the piece behind it.
A discovered attack works like a curtain: one piece steps off the line and unveils the long-range piece behind it. The beauty is that the moving piece can create a second threat of its own — two attacks in one move. Look for your stacked pairs: a bishop or rook behind a knight or pawn, aimed through them at something valuable. Send the front piece to the most aggressive square — a discovery without a second threat wastes half its power.
About this position
These pieces come from starting position #870.
SP-870 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).
The king starts on d1, the rooks on b1 and e1, the queen on a1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the ThroneScout family; read right to left it becomes position 86.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 10 of 100 — class D — largest edge. Engine evaluation of the starting position: +44 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 55.0% (95% CI 41.3–67.9%).
Explore position #870Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-870
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