Chess960 tactic on a4 (a3)
c9-11833naming 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: a forcing sequence that ends the game — the king has no escape.
Mate in 4: a forced checkmate in four moves — every reply is covered.
Difficulty 2120 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.
This is a forced mating attack. Start from the enemy king: which of its squares are already covered, and which move takes away the rest while keeping the king in check? Forcing moves — checks and captures — are what turn an attack into mate.
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.
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 d1, queen a3, rook e1, bishop h1, knight e5, pawn a2 f2 h3 f4.
Black: king e8, rook a8 c8, bishop f8, pawn b6 h6 a7 e7 f7.
9 white and 9 black pieces are on the board; the puzzle position arises after move 24.
The position in numbers
White are ahead by 6 points of material (24 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 d1, the black king on e8.
It is White to move on move 24, with 41 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 5. Files fully open (no pawns of either colour): c, d, g — natural highways for the rooks and queen. Half-open for White: b, e.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
24. Qa4+ b5 25. Qxb5+ Rc6 26. Qxc6+ Kd8 27. Nxf7#
Why it works
- Best move. queen to a4 is exactly what the engine plays (#3).
- Spot on — queen to b5 (#2).
- Precise: queen to c6 is the top choice (#1).
- Best move. knight to f7 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead b5, then Qxb5+ and you stay on top.
Move by move
- 24. Qa4+ — queen to a4 with check
- b5 — pawn to b5
- 25. Qxb5+ — queen to b5 (capture) with check
- Rc6 — rook to c6
- 26. Qxc6+ — queen to c6 (capture) with check
- Kd8 — king to d8
- 27. Nxf7# — knight to f7 (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.
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.
Royal fork
A fork with check: the king must move, and the second piece is lost.
A royal fork is a fork with check — one of the two targets is the king itself. The check must be answered first, so nobody is left to rescue the second piece. Look for squares where your piece gives check and simultaneously attacks an undefended queen or rook. It is the most reliable fork of all, because your opponent literally has no choice.
About this position
These pieces come from starting position #791.
SP-791 · ThroneGuard — King home on d or e, knights kept off the a- and h-files — the family of the standard starting array.
The king starts on d1, the rooks on a1 and f1, the queen on b1.
The kingside rook already stands on f1, so castling short moves only the king, from d1 to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 162.
The engine's main line opens with c3.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #791Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-791
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