Mate in 3: queen to b6 (f2·2)
c9-23492naming 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 d1, queen f2, rook e1 c6, bishop h1 a5, knight f5, pawn b2 c2 b3 f3 g4 h4 e5.
Black: king b8, queen g8, rook d8 e8, knight f4, pawn b4 g5 d6 e7 f7 h7.
14 white and 11 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
White are ahead by 7 points of material (35 against 28; 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 b8.
It is White to move on move 19, with 46 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 7 pawns, Black 6. Files fully open (no pawns of either colour): a — natural highways for the rooks and queen. Half-open for White: d.
White hold the bishop pair, an edge in open lines. 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
19. Qb6+ Ka8 20. Qa6+ Kb8 21. Bc7#
Why it works
- Best move. queen to b6 is exactly what the engine plays (#2).
- Spot on — queen to a6 (#1).
- Precise: bishop to c7 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Ka8, then Qa6+ and you stay on top.
Move by move
- 19. Qb6+ — queen to b6 with check
- Ka8 — king to a8
- 20. Qa6+ — queen to a6 with check
- Kb8 — king to b8
- 21. Bc7# — bishop to c7 and it is checkmate
Types in this puzzle
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.
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.
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 #375.
SP-375 · ThroneScout — Centre-file king, rim knight: 204 of the 960 positions share this pattern.
The king starts on d1, the rooks on b1 and e1, the queen on g1.
Castling ends where it always does: king to g1 and rook to f1 on the short side, king to c1 and rook to d1 on the long one.
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: a2.
The setup belongs to the ThroneScout family; read right to left it becomes position 290.
The engine's main line opens with f4.
Morozov Balance Index: 20 of 100 — class D — largest edge. Engine evaluation of the starting position: +37 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #375Provenance
Mined from the project's engine self-play games.
Pack 012 · SP-375
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