Attack on the uncastled king: bishop to c7 (a5·3)
c9-20035naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1630 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.
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.
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.
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 d1, queen a7, rook c1 f1, bishop h1 a5, knight b1, pawn c2 e2 g2 d3 f4 c6.
Black: king d8, queen g7, rook c8 f8, bishop b2 e8, knight c7, pawn h4 f5 d7 e7 h7.
13 white and 12 black pieces are on the board; the puzzle position arises after move 12.
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 d1, the black king on d8.
It is White to move on move 12, with 35 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): a, b — natural highways for the rooks and queen. Half-open for White: h.
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
12. Bxc7+ Rxc7 13. Qb8+ Rc8 14. c7#
Why it works
- Great move! bishop to c7 keeps the pressure (#2).
- Well found: queen to b8 (#1).
- Precise: pawn to c7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Rxc7, then Qb8+ and you stay on top.
Move by move
- 12. Bxc7+ — bishop to c7 (capture) with check
- Rxc7 — rook to c7 (capture)
- 13. Qb8+ — queen to b8 with check
- Rc8 — rook to c8
- 14. c7# — pawn to c7 and it is checkmate
Types in this puzzle
Pawn mate
The humblest soldier delivers the final blow.
The pawn mate lets the humblest soldier land the final blow. It happens to a king stuck among its own and enemy pieces: the pawn strikes diagonally from one square away and there is nowhere left to run. The sign: the squares around the king are covered or occupied, and your pawn stands one step from striking distance. Never write pawns out of your attack — their blows are the cheapest and therefore the most humiliating.
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 #91.
SP-91 · ThroneScout — A central king (d or e), but with a knight posted out on the a- or h-file.
The king starts on d1, the rooks on c1 and f1, the queen on g1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The second rank carries 2 pawns with no defender at all: a2, b2.
The setup belongs to the ThroneScout family; read right to left it becomes position 865.
The engine's main line opens with g4.
Morozov Balance Index: 26 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +34 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #91Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-91
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