Mate in 3: knight to b5 (c3·3)
c9-24796naming 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 d1, queen g3, rook f8, knight c3, pawn b2 a3 c4.
Black: king a7, queen e6, pawn a4 c5 g5 b7 h7.
7 white and 7 black pieces are on the board; the puzzle position arises after move 36.
The position in numbers
White are ahead by 6 points of material (20 against 14; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on d1, the black king on a7.
It is White to move on move 36, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 5. Files fully open (no pawns of either colour): d, e, f — natural highways for the rooks and queen. Half-open for White: g, h.
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
36. Nb5+ Ka6 37. Ra8+ Kb6 38. Qc7#
Why it works
- Best move. knight to b5 is exactly what the engine plays (#2).
- Spot on — rook to a8 (#1).
- Precise: queen to c7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka6, then Ra8+ and you stay on top.
Move by move
- 36. Nb5+ — knight to b5 with check
- Ka6 — king to a6
- 37. Ra8+ — rook to a8 with check
- Kb6 — king to b6
- 38. Qc7# — queen to c7 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 #902.
SP-902 · RampartScout — The king starts on b or g while a knight begins on the a- or h-file — the smallest family.
The king starts on b1, the rooks on a1 and e1, the queen on d1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
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 RampartScout family; read right to left it becomes position 54.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 2 of 100 — class D — largest edge. Engine evaluation of the starting position: +62 centipawns for White (depth 48, 400 000 000 nodes).
In 50 self-play games White scored 54.0% (95% CI 40.4–67.0%).
Explore position #902Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-902
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