Attack on the uncastled king: knight to b5 (c3·19)
c9-26744naming 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.
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 1200 ShuffleRating — club-player level.
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.
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 e2, rook a1 d1, bishop d2, knight c3 f3, pawn f2 g2 h2 b3 e3.
Black: king d8, queen b5, rook c8 e8, knight h6 b8, pawn d4 f5 a7 c7 d7 g7 h7.
11 white and 13 black pieces are on the board; the puzzle position arises after move 18.
The position in numbers
Black are ahead by 8 points of material (24 against 32; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e2, the black king on d8.
It is White to move on move 18, with 2 legal replies to weigh — only the line that keeps the advantage solves the puzzle. White are in check right now, so every reply must answer the check.
White keeps 5 pawns, Black 7. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: a, c, d.
The White king has 1 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
18. Nxb5 dxe3 19. fxe3 Nc6 20. Nxa7 Nxa7 21. Rxa7
Why it works
- Great move! knight to b5 keeps the pressure (+4.2).
- Spot on — pawn to e3 (+4.4).
- Precise: knight to a7 is the top choice (+4.3).
- Great move! rook to a7 keeps the pressure (+4.4).
- You win a piece — the queen.
- If instead dxe3, then fxe3 and you win the queen.
Move by move
- 18. Nxb5 — knight to b5 (capture)
- dxe3 — pawn to e3 (capture)
- 19. fxe3 — pawn to e3 (capture)
- Nc6 — knight to c6
- 20. Nxa7 — knight to a7 (capture)
- Nxa7 — knight to a7 (capture)
- 21. Rxa7 — rook to a7 (capture)
Types in this puzzle
Winning exchange
A forced series of captures on one square ends in your favour.
A winning exchange is a forced series of captures on one square that leaves you ahead in material. It is pure arithmetic: count the attackers and defenders of the square and note the value of every piece in the queue. Capture in the right order — cheap pieces first, expensive ones later — or a winning trade turns into a losing one. The classic error is stopping the count halfway and missing the opponent's final recapture.
Mate defense
Mate is threatened — parry it and stay on top.
Mate defense: your opponent is one move from mating you — but it is your turn, and that changes everything. Find the defense that kills the mating threat while keeping your advantage: often a check or a counter-threat that leaves no time for the mate. First name the exact square where the mate would land — otherwise you are defending blind. The mistake is playing a "defensive" move that does not actually remove the threat.
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 #202.
SP-202 · ThroneGuard — A centre-file king with no knight on the edge; a position and its mirror twin always share this family.
The king starts on d1, the rooks on c1 and h1, the queen on a1.
Castling long simply swaps the two pieces: the king on d1 and the rook on c1 trade places.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the ThroneGuard family; read right to left it becomes position 661.
The engine's main line opens with b4.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 47, 400 000 000 nodes).
Explore position #202Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-202
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