Attack on the uncastled king: pawn to f7 (e6·4)
c9-20878naming 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 3: a forced sequence that ends in checkmate.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Difficulty 1980 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.
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.
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 h1, queen h2, rook e1 f1, bishop f4 g6, knight a1, pawn b2 g2 h4 a5 e6.
Black: king f8, queen h8, rook g8, bishop b6 d7, knight f7, pawn c4 h5 a6 b7 c7 g7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 4 points of material (33 against 29; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on h1, the black king on f8.
It is White to move on move 21, with 40 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 6. Files fully open (no pawns of either colour): d, f — natural highways for the rooks and queen. Half-open for White: c.
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
21. exf7 Bd4 22. Re8+ Bxe8 23. fxe8=Q#
Why it works
- Best move. pawn to f7 is exactly what the engine plays (#2).
- Spot on — rook to e8 (#1).
- Precise: pawn to e8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Bd4, then Re8+ and you win the knight.
Move by move
- 21. exf7 — pawn to f7 (capture)
- Bd4 — bishop to d4
- 22. Re8+ — rook to e8 with check
- Bxe8 — bishop to e8 (capture)
- 23. fxe8=Q# — pawn to e8 (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 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.
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 #84.
SP-84 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).
The king starts on f1, the rooks on e1 and g1, the queen on h1.
Castling short simply swaps the two pieces: the king on f1 and the rook on g1 trade places.
The bishops stand on b1 and c1; their long diagonals reach h7 and h6 once the c- and d-pawns step aside.
Every pawn on the second rank is defended from the very first move.
The setup belongs to the BastionScout family; read right to left it becomes position 878.
The engine's main line opens with d4, putting a pawn straight into the centre.
Morozov Balance Index: 80 of 100 — class A — most balanced. Engine evaluation of the starting position: +17 centipawns for White (depth 44, 400 000 000 nodes).
Explore position #84Provenance
Mined from the project's engine self-play games.
Pack 014 · SP-84
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