Attack on the uncastled king: pawn to b7 (a6·11)
c9-22226naming 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 1700 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.
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 a7, rook b1 h1, bishop e1, knight b3 g3, pawn b2 c2 h2 f3 f4 a6.
Black: king c8, queen c4, rook b8 h8, bishop d8, knight c7 f8, pawn c5 f5 g6 b7 h7.
13 white and 12 black pieces are on the board; the puzzle position arises after move 14.
The position in numbers
White are ahead by 1 points of material (34 against 33; 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 14, with 30 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): d, e — natural highways for the rooks and queen. Half-open for White: g.
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
14. axb7+ Rxb7 15. Qxb7+ Kxb7 16. Na5+ Kc8 17. Nxc4
Why it works
- Great move! pawn to b7 keeps the pressure (+5.8).
- Well found: queen to b7 (+5.8).
- Strong! knight to a5 is the sharp choice (+5.8).
- Great move! knight to c4 keeps the pressure (+5.8).
- You win a piece — the queen.
- If instead Rxb7, then Qxb7+ and you win the rook.
Move by move
- 14. axb7+ — pawn to b7 (capture) with check
- Rxb7 — rook to b7 (capture)
- 15. Qxb7+ — queen to b7 (capture) with check
- Kxb7 — king to b7 (capture)
- 16. Na5+ — knight to a5 with check
- Kc8 — king to c8
- 17. Nxc4 — knight to c4 (capture)
Types in this puzzle
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
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.
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 #265.
SP-265 · BastionScout — A c- or f-file king with at least one knight out on the edge.
The king starts on c1, the rooks on b1 and h1, the queen on g1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-pawns step aside.
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 601.
The engine's main line opens with f4.
Morozov Balance Index: 55 of 100 — class B — balanced. Engine evaluation of the starting position: +25 centipawns for White (depth 41, 400 000 000 nodes).
Explore position #265Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-265
Similar puzzles
In your browser or in the Android app. Nothing to install · Free, no ads