Attack on the uncastled king: queen to a7 (a5·9)
c9-26567naming 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 2: the first move creates an unstoppable threat, the second delivers mate.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1450 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.
Mate in two usually opens with a forcing move — a check, a capture or an unstoppable threat — that strips the king of squares or defenders, so the follow-up mate becomes unavoidable. Look for the first move that leaves the opponent only losing replies.
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 a2, queen a5, rook a1 d1, bishop c1, knight b5 e5, pawn b2 a4 d4.
Black: king b8, queen h5, rook c3 d8, bishop c2 f8, knight e2 e7, pawn g4 d5 g5 b7 c7.
10 white and 13 black pieces are on the board; the puzzle position arises after move 23.
The position in numbers
Black are ahead by 5 points of material (31 against 36; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a2, the black king on b8.
It is White to move on move 23, with 34 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 3 pawns, Black 5. Files fully open (no pawns of either colour): e, f, h — natural highways for the rooks and queen. Half-open for White: c, g.
Black hold the bishop pair, an edge in open lines. 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
23. Qa7+ Kc8 24. Qa8#
Why it works
- Great move! queen to a7 keeps the pressure (#1).
- Well found: queen to a8 (#).
- The line ends in a forced mate in 2.
- If instead Kc8, then Qa8# and it is mate.
Move by move
- 23. Qa7+ — queen to a7 with check
- Kc8 — king to c8
- 24. Qa8# — queen to a8 and it is checkmate
Types in this puzzle
Mate in 2
A forced checkmate in two moves.
Mate in two: your move, any reply, then the mating blow. Start with the most forcing first moves — checks and sacrifices that shrink the opponent's options to almost nothing. Against every single reply you must have a mate ready, so check them all without exception. The common failure is analyzing the pretty defense and forgetting the boring one.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
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 #950.
SP-950 · RampartGuard — A b- or g-file king and two knights on inner files (b–g).
The king starts on b1, the rooks on a1 and d1, 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 c1 and f1; their long diagonals reach h6 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: f2.
The setup belongs to the RampartGuard family; read right to left it becomes position 6.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 8 of 100 — class D — largest edge. Engine evaluation of the starting position: +45 centipawns for White (depth 48, 400 000 000 nodes).
Explore position #950Provenance
Mined from the project's engine self-play games.
Pack 011 · SP-950
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