Mate in 3: queen to e7 (c5·5)
c9-25465naming 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.
A fork made possible by the Chess960 piece placement.
Difficulty 1630 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.
A set-up fork needs one preparing move before the fork lands — a check that drives the king onto the forking square, or a capture that lines the targets up. Find the preparation first, then the fork it makes possible.
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 c1, queen c5, rook a1 d4, bishop g1 d3, pawn d2 c3 h3 f4 a6.
Black: king c7, queen c6, rook a8 c8, bishop b8 g8, knight e8, pawn g6 h6 a7.
11 white and 10 black pieces are on the board; the puzzle position arises after move 27.
The position in numbers
Black are ahead by 1 points of material (30 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c7.
It is White to move on move 27, with 49 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 3. Files fully open (no pawns of either colour): b, e — natural highways for the rooks and queen. Half-open for White: g.
The White king has 5 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
27. Qe7+ Qd7 28. Qxd7+ Kb6 29. Rb4#
Why it works
- Best move. queen to e7 is exactly what the engine plays (#2).
- Spot on — queen to d7 (#1).
- Precise: rook to b4 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Qd7, then Qxd7+ and you win the queen.
Move by move
- 27. Qe7+ — queen to e7 with check
- Qd7 — queen to d7
- 28. Qxd7+ — queen to d7 (capture) with check
- Kb6 — king to b6
- 29. Rb4# — rook to b4 and it is checkmate
Types in this puzzle
Double-check mate
Double check leaves only king moves — and there are none.
The double-check mate ends the game with check from two pieces at once, leaving the king with nothing. Neither capturing nor blocking works against a double check — only a king move, and here there is none. Look for a discovered check where the front piece checks too: it may even land on a defended square with total impunity. That is why the double check crowns so many of the most beautiful sacrificial combinations.
Setup fork
The random setup allows a fork that classical chess never sees.
A setup fork is a double attack that exists only because of the unusual starting squares — in classical chess these targets never stand side by side. Look for pairs of undefended pieces on your opponent's back rank and for squares from which a knight or pawn hits both at once. Such forks usually appear within the first moves, before the pieces disperse. In every new position, note right away which starting pieces are defended by no one.
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.
About this position
These pieces come from starting position #940.
SP-940 · BastionScout — A knight on the a- or h-file, king on c or f — the mirror twin lands here as well.
The king starts on c1, the rooks on a1 and d1, the queen on f1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and g1; their long diagonals reach h7 and a7 once the c- and f-pawns step aside.
The pawn on b2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the BastionScout family; read right to left it becomes position 28.
The engine's main line opens with a4.
Morozov Balance Index: 59 of 100 — class B — balanced. Engine evaluation of the starting position: +24 centipawns for White (depth 49, 400 000 000 nodes).
Explore position #940Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-940
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