Attack on the uncastled king: queen to b7 (h1·27)
c9-22575naming 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.
A piece strikes across the board from its Chess960 starting square.
Mate in 3: a forced sequence that ends in checkmate.
A fork made possible by the Chess960 piece placement.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1990 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.
From some Chess960 setups a bishop or queen rakes a long diagonal straight from move one. Trace those long-range lines into the enemy camp: a single opened file or diagonal can create an immediate pin, skewer or mating threat.
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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 b1, queen h1, rook a1 c1, bishop d1 e1, knight d4 a5, pawn a2 b2 c2 e2 h2 d3 g3 f4.
Black: king b8, queen g8, rook a8 c8, bishop d8 e8, knight c5 f6, pawn f5 d6 g6 b7 c7 e7 h7.
16 white and 15 black pieces are on the board; the puzzle position arises after move 9.
The position in numbers
White are ahead by 1 points of material (39 against 38; 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 9, with 33 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 8 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in.
The White king has 0 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
9. Qxb7+ Nxb7 10. Nac6+ Bxc6 11. Nxc6#
Why it works
- Great move! queen to b7 keeps the pressure (#2).
- Spot on — knight to c6 (#1).
- Strong! knight to c6 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Nxb7, then Nac6+ and you stay on top.
Move by move
- 9. Qxb7+ — queen to b7 (capture) with check
- Nxb7 — knight to b7 (capture)
- 10. Nac6+ — knight to c6 with check
- Bxc6 — bishop to c6 (capture)
- 11. Nxc6# — knight to c6 (capture) and it is checkmate
Types in this puzzle
Knight mate
The knight lands the killing blow from its unique angle.
In a knight mate the final blow comes from the knight — the only piece whose check can never be blocked. That makes it lethal against a cramped king: only a king move or capturing the knight itself can help. The sign: the squares around the king are occupied or covered, and there is a hop from which the knight checks while staying untouchable. Bring the knight over early — it is slower than the long-range pieces, but its strike cannot be parried.
Long-range opener
From its unusual home square a long-range piece strikes across the board.
The long-range opener: a bishop, rook or queen strikes across the whole board straight from its starting area. In Chess960 the long-range pieces sit on unfamiliar squares, and a single pawn move can uncover a shot deep into the enemy camp. In the opening, trace with your eyes the diagonals and files of every long-range piece — yours and theirs. The mistake is pushing a pawn without checking whose line you have just opened.
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.
About this position
These pieces come from starting position #953.
SP-953 · RampartGuard — A wing king (b/g) with no knight on the a- or h-file.
The king starts on b1, the rooks on a1 and c1, the queen on h1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
The bishops stand on d1 and e1; their long diagonals reach h5 and a5 once the e- and d-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 9.
The engine's main line opens with a4.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #953Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-953
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