Mate in 3: knight to c6 (a7·3)
c9-09877naming 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 2170 ShuffleRating — expert level — few solve it at first try.
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 a1, queen c4, rook b1 b7, knight c2 a7, pawn h2 c3 g3 a4.
Black: king a8, queen h8, rook d3, bishop c5, pawn g4 a5 h5 d6 c7.
10 white and 9 black pieces are on the board; the puzzle position arises after move 28.
The position in numbers
White are ahead by 7 points of material (29 against 22; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a1, the black king on a8.
It is White to move on move 28, with 45 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 5. Files fully open (no pawns of either colour): b, e, f — natural highways for the rooks and queen. Half-open for White: d.
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. Nc6 Qxc3+ 29. Qxc3 Rxc3 30. Rb8#
Why it works
- Sensible development: knight to c6.
- Spot on — queen to c3 (#1).
- Precise: rook to b8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Qxc3+, then Qxc3 and you win the queen.
Move by move
- 28. Nc6 — knight to c6
- Qxc3+ — queen to c3 (capture) with check
- 29. Qxc3 — queen to c3 (capture)
- Rxc3 — rook to c3 (capture)
- 30. Rb8# — rook to b8 and it is checkmate
Types in this puzzle
Arabian mate
Rook and knight — the oldest mate: the rook strikes next to the cornered king.
The Arabian mate is the oldest named pattern: the king is driven into the corner and the rook mates right next to it, guarded by a knight. The geometry is exact: king on h8, rook striking from h7, knight on f6 both protecting the rook and covering g8. The knight is irreplaceable — only it can guard the rook at point-blank range and hold the escape square at once. Look for the pattern when your knight is anchored two steps from the enemy corner.
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.
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
About this position
These pieces come from starting position #758.
SP-758 · RampartGuard — A b- or g-file king and two knights on inner files (b–g).
The king starts on b1, the rooks on a1 and g1, the queen on h1.
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.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the RampartGuard family; read right to left it becomes position 390.
The engine's main line opens with a4.
Morozov Balance Index: 34 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +31 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #758Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-758
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