Attack on the uncastled king: bishop to c7 (f4·9)
c9-26464naming 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 1560 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, queen d5, rook e1, bishop h1 f4, knight a1 f1, pawn c2 d2 h2 a3 f5.
Black: king c8, queen c7, rook e8, pawn b5 b7 d7 e7 h7.
12 white and 8 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
White are ahead by 12 points of material (31 against 19; 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 17, with 49 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): g — natural highways for the rooks and queen. Half-open for White: b, e.
White hold the bishop pair, an edge in open lines. 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
17. Bxc7 d6 18. Qxb7+ Kd7 19. Bc6#
Why it works
- Great move! bishop to c7 keeps the pressure (#2).
- Spot on — queen to b7 (#1).
- Precise: bishop to c6 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead d6, then Qxb7+ and you win the queen.
Move by move
- 17. Bxc7 — bishop to c7 (capture)
- d6 — pawn to d6
- 18. Qxb7+ — queen to b7 (capture) with check
- Kd7 — king to d7
- 19. Bc6# — bishop to c6 and it is checkmate
Types in this puzzle
Boden's mate
Two bishops cross their diagonals over a king blocked by its own pieces.
Boden's mate crosses two bishop diagonals over a king blocked by its own pieces. The classic victim has castled on the queenside: its own rook and pawns have stolen the escape squares, and the bishops slash crosswise. The trigger is usually a queen sacrifice that blasts open the second diagonal. Whenever the enemy king is boxed in by its friends, ask whether both of your bishops can reach it on crossing diagonals.
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.
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 #351.
SP-351 · BastionScout — Off-centre king plus a rim knight (a/h): 168 positions carry this shape.
The king starts on c1, the rooks on b1 and e1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 320.
The engine's main line opens with f4.
Morozov Balance Index: 83 of 100 — class A — most balanced. Engine evaluation of the starting position: +16 centipawns for White (depth 42, 400 000 000 nodes).
Explore position #351Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-351
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