Attack on the uncastled king: pawn to h7 (g6·4)
c9-11901naming 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.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
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.
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 g1, queen g3, rook a1 h3, bishop f1, knight c3 d7, pawn a2 c2 g2 e3 b4 d4 g6.
Black: king g8, rook h7 b8, bishop b7, pawn a5 b5 e6 h6 c7 f7.
14 white and 10 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 16 points of material (35 against 19; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on g1, the black king on g8.
It is White to move on move 21, with 48 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. No file is fully open, so the heavy pieces have to be pried in. Half-open for White: f, h.
The White king has 3 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
21. gxh7+ Kh8 22. Nf6 axb4 23. Qg8+ Rxg8 24. hxg8=Q#
Why it works
- Best move. pawn to h7 is exactly what the engine plays (#3).
- knight to f6 develops smoothly.
- Precise: queen to g8 is the top choice (#1).
- Best move. pawn to g8 is exactly what the engine plays (#).
- The line ends in a forced mate in 4.
- If instead Kh8, then Nf6 and you win the rook.
Move by move
- 21. gxh7+ — pawn to h7 (capture) with check
- Kh8 — king to h8
- 22. Nf6 — knight to f6
- axb4 — pawn to b4 (capture)
- 23. Qg8+ — queen to g8 with check
- Rxg8 — rook to g8 (capture)
- 24. hxg8=Q# — pawn to g8 (capture) and it is checkmate
Types in this puzzle
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.
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.
Promotion mate
The pawn promotes — and the new piece mates on the spot.
In a promotion mate the pawn takes its final step and the newborn piece mates on the spot. Sometimes the hero is a knight rather than a queen — it checks from the promotion square in a way no queen can. The sign: the enemy king lingers near the promotion square while your pieces already control its escape routes. When counting pawn races, always check whether the promotion itself is mate — that gains you a full tempo in the evaluation.
About this position
These pieces come from starting position #418.
SP-418 · 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 g1, the rooks on b1 and h1, the queen on d1.
The king already stands on its castled square, so castling short moves only the rook, from h1 to f1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
The pawn on f2 is defended by the king alone — the classic soft spot of the standard setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 727.
The engine's main line opens with c4.
Morozov Balance Index: 100 of 100 — class A — most balanced. Engine evaluation of the starting position: -2 centipawns for White (depth 47, 400 000 000 nodes).
In 50 self-play games White scored 51.0% (95% CI 37.6–64.3%).
Explore position #418Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-418
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