Attack on the uncastled king: knight to d7 (c5·19)
c9-23465naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1200 ShuffleRating — club-player level.
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.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 c1, rook e1 e3, bishop d1 d4, knight g3 c5, pawn a2 c2 f2 g2 b4 e4 h4.
Black: king c8, queen d7, rook b6 e8, bishop a8 d8, knight h6, pawn b5 d5 a6 f6 g6 c7 h7.
14 white and 14 black pieces are on the board; the puzzle position arises after move 16.
The position in numbers
Black are ahead by 6 points of material (29 against 35; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 16, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: d.
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
16. Nxd7 Kxd7 17. exd5 Rxe3 18. Bxe3 Nf7 19. Bxb6
Why it works
- Great move! knight to d7 keeps the pressure (+4.0).
- Spot on — pawn to d5 (+4.1).
- Strong! bishop to e3 is the sharp choice (+4.2).
- Best move. bishop to b6 is exactly what the engine plays (+3.9).
- You win a piece — the queen.
- If instead Kxd7, then exd5 and you win the queen.
Move by move
- 16. Nxd7 — knight to d7 (capture)
- Kxd7 — king to d7 (capture)
- 17. exd5 — pawn to d5 (capture)
- Rxe3 — rook to e3 (capture)
- 18. Bxe3 — bishop to e3 (capture)
- Nf7 — knight to f7
- 19. Bxb6 — bishop to b6 (capture)
Types in this puzzle
Bishop fork
The bishop attacks two pieces on crossing diagonals at once.
A bishop fork happens when the bishop lands where two diagonals cross and attacks a target on each of them. Both victims must stand on the bishop's color — that is the first thing to verify. Scan for loose enemy pieces that share the color of squares with their own king or queen. A common sin is placing your own pieces on squares of one color and handing your opponent exactly this geometry.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
About this position
These pieces come from starting position #945.
SP-945 · 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 b1 and e1, the queen on h1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The second rank carries 2 pawns with no defender at all: a2, f2.
The setup belongs to the BastionGuard family; read right to left it becomes position 11.
The engine's main line opens with f4.
Morozov Balance Index: 9 of 100 — class D — largest edge. Engine evaluation of the starting position: +44 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #945Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-945
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