Attack on the uncastled king: queen to b6 (b3·2)
c9-12509naming 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 4: a forced checkmate in four moves — every reply is covered.
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 2250 ShuffleRating — expert level — few solve it at first try.
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.
A mate in four is a longer forced net: each of your moves is a check or an irresistible threat, and the king is driven step by step to a square where it is finally trapped. Verify that the defender has exactly one reply at every branch.
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 b1, queen b3, rook a1 f5, bishop e3, knight c5, pawn b2 h2 c3 g3 a4.
Black: king b8, rook a8 h8, knight b6, pawn a5 h5 c6 b7 g7.
11 white and 9 black pieces are on the board; the puzzle position arises after move 23.
The position in numbers
White are ahead by 12 points of material (30 against 18; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on b8.
It is White to move on move 23, with 47 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): d, e, f — natural highways for the rooks and queen.
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
23. Qxb6 Ra7 24. Rf7 g6 25. Rxb7+ Kc8 26. Qc7#
Why it works
- Best move. queen to b6 is exactly what the engine plays (#3).
- rook to f7 develops smoothly.
- Precise: rook to b7 is the top choice (#1).
- Best move. queen to c7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Ra7, then Rf7 and you win the knight.
Move by move
- 23. Qxb6 — queen to b6 (capture)
- Ra7 — rook to a7
- 24. Rf7 — rook to f7
- g6 — pawn to g6
- 25. Rxb7+ — rook to b7 (capture) with check
- Kc8 — king to c8
- 26. Qc7# — queen to c7 and it is checkmate
Types in this puzzle
Ladder mate
Two heavy pieces climb line by line, cutting off every retreat.
The ladder mate uses two heavy pieces climbing rung by rung: one cuts the king off along a line, the other checks on the next line, driving him toward the edge. It is the classic two-rook technique — check, the king retreats one rank, the other rook checks, until mate on the last rank. The only danger is the king creeping close enough to attack one of your rooks. If it does, simply slide that rook to the far side of the same line.
Mate in 4+
A long forced mating combination.
Mate in four or longer is a marathon of forcing moves where the grip must never loosen. The tools are the same: checks, double threats and sacrifices that deny the opponent a single free tempo. Do not juggle the whole tree at once — walk the main line all the way to mate first, then verify the side branches. If somewhere the defender finds one quiet move that holds, your very first move was wrong.
Supported queen mate
The queen delivers mate face to face, protected by a friend.
The supported queen mate is the most common pattern of all: the queen lands next to the king and mates because a friendly piece or pawn protects her. The king is helpless — capturing is impossible, and the queen covers every neighboring square herself. Hunt for a protected square beside the enemy king: a knight, bishop or pawn eyeing it turns her invasion into mate. Verify one thing — that the square really is defended, or the king eats her.
About this position
These pieces come from starting position #730.
SP-730 · RampartGuard — Both knights begin on inner files while the king sits on the wing (b/g); mirror twins stay together in this family.
The king starts on b1, the rooks on a1 and h1, the queen on d1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
The pawn on b2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 421.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 13 of 100 — class D — largest edge. Engine evaluation of the starting position: +41 centipawns for White (depth 43, 400 000 000 nodes).
Explore position #730Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-730
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