Mate in 3: knight to b5 (c3·7)
c9-12493naming 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 1980 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 b2, rook c2, bishop g4, knight c3, pawn h2 b3 f3 a4.
Black: king a7, queen d1, pawn a5 c5 d5 g5 h5 b7.
9 white and 8 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
White are ahead by 9 points of material (24 against 15; 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 a7.
It is White to move on move 39, with 26 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): e — natural highways for the rooks and queen. Half-open for White: c, d, g.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. Nb5+ Ka6 40. Qf6+ b6 41. Bc8#
Why it works
- Best move. knight to b5 is exactly what the engine plays (#2).
- Spot on — queen to f6 (#1).
- Precise: bishop to c8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka6, then Qf6+ and you stay on top.
Move by move
- 39. Nb5+ — knight to b5 with check
- Ka6 — king to a6
- 40. Qf6+ — queen to f6 with check
- b6 — pawn to b6
- 41. Bc8# — bishop to c8 and it is checkmate
Types in this puzzle
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.
Absolute pin
A piece is pinned against its king — it cannot legally move.
An absolute pin freezes a piece on the line between its own king and your long-range attacker: moving it is simply illegal. The pattern is three units on one straight line — your bishop, rook or queen, an enemy piece, and the enemy king behind it. A pinned piece neither attacks nor defends anything: treat it as if it were off the board. Pile up on it, ideally with a pawn, because running away is against the rules.
About this position
These pieces come from starting position #837.
SP-837 · RampartScout — Wing king plus a rim knight, and only 72 positions qualify — the rarest pattern of all.
The king starts on b1, the rooks on a1 and f1, the queen on g1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on c1 and d1; their long diagonals reach h6 and h5 once the d- and e-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the RampartScout family; read right to left it becomes position 122.
The engine's main line opens with a4.
Morozov Balance Index: 51 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +26 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #837Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-837
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