Attack on the uncastled king: queen to f5 (b1·13)
c9-23647naming 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 1760 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 f1, queen b1, rook d1 h1, bishop c6, knight d2, pawn a2 e2 g2 h2 b3.
Black: king f8, rook d8 h8, pawn d4 f5 b6 a7 e7 g7 h7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 17.
The position in numbers
White are ahead by 13 points of material (30 against 17; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on f1, the black king on f8.
It is White to move on move 17, with 35 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 7. Files fully open (no pawns of either colour): c — natural highways for the rooks and queen. Half-open for White: d, f.
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
17. Qxf5+ Kg8 18. Qe6+ Kf8 19. O-O#
Why it works
- Great move! queen to f5 keeps the pressure (#2).
- Spot on — queen to e6 (#1).
- Precise: king to g1 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kg8, then Qe6+ and you stay on top.
Move by move
- 17. Qxf5+ — queen to f5 (capture) with check
- Kg8 — king to g8
- 18. Qe6+ — queen to e6 with check
- Kf8 — king to f8
- 19. O-O# — king to h1 and it is checkmate
Types in this puzzle
Castling mate
The rarest gem: castling itself delivers checkmate — a Chess960 speciality.
The castling mate is the rarest gem of all: the act of castling itself delivers checkmate. Chess960 makes it far more likely than classical chess — king and rook start on unusual squares, so castling can transform the attacking geometry in one move. The sign: the enemy king stands on the line where your rook will land, with the nearby squares already covered. Treat castling as a fighting move — the only move that moves two pieces at once.
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.
Discovered mate
A piece steps aside — and the one behind it delivers mate.
In a discovered mate the piece that moves is not the one that mates — the long-range piece behind it delivers the blow. The moving piece is completely free: it can land anywhere, ideally stealing the king's last squares or guarding key points. Look for your rook, bishop or queen lined up with the enemy king, with exactly one of your own pieces in between. When choosing the unveiling move, remember its second job — shutting the king's escape door.
About this position
These pieces come from starting position #488.
SP-488 · BastionGuard — A c- or f-file king and two knights on inner files (b–g).
The king starts on f1, the rooks on c1 and h1, the queen on a1.
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 b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
The pawn on g2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionGuard family; read right to left it becomes position 573.
The engine's main line opens with c4.
Morozov Balance Index: 18 of 100 — class D — largest edge. Engine evaluation of the starting position: +38 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #488Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-488
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