Mate in 3: queen to b5 (d3·2)
c9-18898naming 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 1760 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 b1, queen d3, rook e3, bishop g1 b7, knight g3, pawn b2 c2 e2 h2 a4 f4.
Black: king d7, queen g7, rook d8 f8, bishop b3 h8, knight e7, pawn a5 f5 d6 c7 h7.
12 white and 12 black pieces are on the board; the puzzle position arises after move 19.
The position in numbers
Black are ahead by 4 points of material (29 against 33; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on b1, the black king on d7.
It is White to move on move 19, with 39 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 6 pawns, Black 5. Files fully open (no pawns of either colour): g — natural highways for the rooks and queen. Half-open for White: d.
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
19. Qb5+ c6 20. Bxc6+ Nxc6 21. Qb7#
Why it works
- Great move! queen to b5 keeps the pressure (#2).
- Well found: bishop to c6 (#1).
- Strong! queen to b7 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead c6, then Bxc6+ and you stay on top.
Move by move
- 19. Qb5+ — queen to b5 with check
- c6 — pawn to c6
- 20. Bxc6+ — bishop to c6 (capture) with check
- Nxc6 — knight to c6 (capture)
- 21. Qb7# — queen to b7 and it is checkmate
Types in this puzzle
Epaulette mate
The king's own pieces flank it like epaulettes — mate comes head-on.
In the epaulette mate the king stands between two of its own pieces — most often rooks — like an officer wearing epaulettes. The side squares are blocked by friends, there is no retreat, and the queen mates head-on from directly in front of the king. The sign: a king on the edge rank with both neighboring squares on that rank occupied by its own pieces. Remember, extra defenders crowding the king can be deadlier than no defenders at all.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
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.
About this position
These pieces come from starting position #847.
SP-847 · RampartGuard — The king starts out on a wing file, b or g, with neither knight in a corner.
The king starts on b1, the rooks on a1 and d1, the queen on e1.
From b1 the king makes the longest journey Chess960 allows when castling short: five squares to g1.
A bishop starts in the corner on h1: it has a single diagonal, which the g-pawn unlocks, running out to a8.
The pawn on b2, c2 is defended by the king alone — the same soft spot f2 is in the classical setup.
The setup belongs to the RampartGuard family; read right to left it becomes position 112.
The engine's main line opens with a4.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 46, 400 000 000 nodes).
Explore position #847Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-847
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