Attack on the uncastled king: bishop to b8 (a7)
c9-01077naming 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 780 ShuffleRating — for beginners taking their first steps in Chess960 tactics.
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 g1, rook b1 h1, bishop a4 a7, knight d1 b3, pawn b2 c2 d2 g2 h2 a3 f3 e4.
Black: king c8, queen g8, rook b8 h8, bishop e8 f8, knight a8 d8, pawn b5 e5 h5 f6 c7 d7 g7.
16 white and 15 black pieces are on the board; the puzzle position arises after move 9.
The position in numbers
White are ahead by 1 points of material (39 against 38; 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 9, with 31 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in.
The White king has 0 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
9. Bxb8 bxa4 10. Qa7 axb3 11. Qxa8
Why it works
- Brilliant! The bishop on b8 is a sacrifice that works — you stand better (+3.0).
- Well found: queen to a7 (+3.1).
- Strong! queen to a8 is the sharp choice (+3.1).
- You reach a winning position (+3.1).
- If instead bxa4, then Qa7 and you stay on top.
Move by move
- 9. Bxb8 — bishop to b8 (capture)
Types in this puzzle
Corner bishop
A bishop born in the corner rakes the longest diagonal.
The corner bishop: in Chess960 a bishop often starts on a1 or h1, staring down the longest diagonal from birth. One pawn move and it fires across the entire board, hitting a rook or king in the far corner. In every starting position inspect the long diagonals: whose bishop sits in the corner, what blocks its path, which pawn move opens the line. The mistake is noticing the enemy corner bishop only after it has collected its loot.
Winning blow
Find the strike that wins material by force.
A winning blow is a forced material gain that does not fit a single textbook motif. The general tactical recipe applies: spot loose pieces, an awkwardly placed king, overloaded lines. Go through the forcing moves in order of violence — checks, captures, threats — because most combinations start with one of them. Do not judge by feel: calculate the concrete line until the outcome is beyond doubt.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #266.
SP-266 · BastionScout — The king starts one file off-centre, on c or f, and a knight begins in a corner.
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 e1 and f1; their long diagonals reach a5 and a6 once the d- and e-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 597.
The engine's main line opens with Nc3, bringing the knight out to c3.
Morozov Balance Index: 57 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 45, 400 000 000 nodes).
In 50 self-play games White scored 53.0% (95% CI 39.5–66.1%).
Explore position #266Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 001 · SP-266
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