Attack on the uncastled king: queen to a3 (b2·2)
c9-25311naming 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 f2, queen b2, rook d1 g1, bishop b1, knight e2 f5, pawn a2 c2 b3 e3 f3 g4 h5.
Black: king f8, queen a5, rook d8 g8, bishop e8, knight b6 b8, pawn a4 c4 d5 e5 f7 g7 h7.
14 white and 14 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Material is level — 35 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on f2, the black king on f8.
It is White to move on move 18, with 42 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: d.
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
18. Qa3+ Qb4 19. Qxb4+ Rd6 20. Qxd6#
Why it works
- Great move! queen to a3 keeps the pressure (#2).
- Well found: queen to b4 (#1).
- Strong! queen to d6 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Qb4, then Qxb4+ and you win the queen.
Move by move
- 18. Qa3+ — queen to a3 with check
- Qb4 — queen to b4
- 19. Qxb4+ — queen to b4 (capture) with check
- Rd6 — rook to d6
- 20. Qxd6# — queen to d6 (capture) and it is checkmate
Types in this puzzle
Epaulette mate
The king's own pieces flank it like epaulettes — mate comes head-on.
In the epaulette mate the king stands between two of its own pieces — most often rooks — like an officer wearing epaulettes. The side squares are blocked by friends, there is no retreat, and the queen mates head-on from directly in front of the king. The sign: a king on the edge rank with both neighboring squares on that rank occupied by its own pieces. Remember, extra defenders crowding the king can be deadlier than no defenders at all.
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 #296.
SP-296 · BastionScout — The king starts one file off-centre, on c or f, and a knight begins in a corner.
The king starts on f1, the rooks on d1 and g1, the queen on a1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionScout family; read right to left it becomes position 381.
The engine's main line opens with Ng3, bringing the knight out to g3.
Morozov Balance Index: 51 of 100 — class B — balanced. Engine evaluation of the starting position: +26 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #296Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-296
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