Attack on the uncastled king: queen to h8 (b2·4)
c9-07658naming 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 e1, queen b2, rook b1 h1, bishop d1 c5, knight a1, pawn d2 g2 b4 e4 f4.
Black: king e8, queen c6, rook b8 h8, bishop a2 d8, knight b6, pawn g6 a7 b7 d7 h7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 15.
The position in numbers
Material is level — 33 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on e1, the black king on e8.
It is White to move on move 15, with 48 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): c — natural highways for the rooks and queen. Half-open for White: a, h.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
15. Qxh8+ Kf7 16. Qf8+ Ke6 17. Bg4#
Why it works
- Great move! queen to h8 keeps the pressure (#2).
- Spot on — queen to f8 (#1).
- Precise: bishop to g4 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kf7, then Qf8+ and you win the rook.
Move by move
- 15. Qxh8+ — queen to h8 (capture) with check
- Kf7 — king to f7
- 16. Qf8+ — queen to f8 with check
- Ke6 — king to e6
- 17. Bg4# — bishop to g4 and it is checkmate
Types in this puzzle
Two-bishop mate
The bishop pair sweeps two adjacent diagonals — the king has nowhere to hide.
The two-bishop mate rakes two adjacent diagonals: one bishop mates while the other seals off the escape squares. The bishops complement each other perfectly — living on opposite colors, together they cover an unbroken strip of the board. The pattern usually appears at the edge or in the corner where the king was pressed beforehand. Treasure the bishop pair until the attack comes — on an open board two adjacent diagonals become a solid wall.
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 #237.
SP-237 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on e1, the rooks on b1 and h1, the queen on c1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
The bishops stand on d1 and g1; their long diagonals reach h5 and a7 once the e- and f-pawns step aside.
The second rank carries 2 pawns with no defender at all: a2, g2.
The setup belongs to the ThroneScout family; read right to left it becomes position 632.
The engine's main line opens with f4.
Morozov Balance Index: 16 of 100 — class D — largest edge. Engine evaluation of the starting position: +39 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #237Provenance
Mined from the project's engine self-play games.
Verified by Stockfish at depth 20+.
Solution forcedness confirmed (verified).
Pack 012 · SP-237
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