Mate in 3: bishop to c6 (d5·2)
c9-13871naming 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 c2, queen f2, rook e1 a6, bishop c3 d5, knight f1, pawn h2 b4 e4 g4 c5 f5.
Black: king b7, queen c8, rook c6 h7, bishop c7, knight d7 f7, pawn h4 b5 e5 g5 f6.
13 white and 12 black pieces are on the board; the puzzle position arises after move 25.
The position in numbers
White are ahead by 1 points of material (34 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 c2, the black king on b7.
It is White to move on move 25, with 47 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): a, d — natural highways for the rooks and queen.
White hold the bishop pair, an edge in open lines. The White king has 7 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
25. Bxc6+ Kxa6 26. Ra1+ Ba5 27. Rxa5#
Why it works
- Great move! bishop to c6 keeps the pressure (#2).
- Spot on — rook to a1 (#1).
- Strong! rook to a5 is the sharp choice (#).
- The line ends in a forced mate in 3.
- If instead Kxa6, then Ra1+ and you stay on top.
Move by move
- 25. Bxc6+ — bishop to c6 (capture) with check
- Kxa6 — king to a6 (capture)
- 26. Ra1+ — rook to a1 with check
- Ba5 — bishop to a5
- 27. Rxa5# — rook to a5 (capture) 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.
Win the pinned piece
The pinned piece cannot run — attack it again and win it.
A pinned piece cannot flee, which means you can win it outright by attacking it one more time. Count attackers against defenders: if you outnumber them, the piece is yours. The best extra attacker is a pawn, since it costs less than anything it might capture. Do not rush the capture — build up the pressure first, then harvest.
About this position
These pieces come from starting position #801.
SP-801 · BastionScout — Off-centre king plus a rim knight (a/h): 168 positions carry this shape.
The king starts on c1, the rooks on b1 and g1, the queen on e1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.
One second-rank pawn starts with no defender at all: a2.
The setup belongs to the BastionScout family; read right to left it becomes position 155.
The engine's main line opens with f4.
Morozov Balance Index: 96 of 100 — class A — most balanced. Engine evaluation of the starting position: +11 centipawns for White (depth 42, 400 000 000 nodes).
In 50 self-play games White scored 51.0% (95% CI 37.6–64.3%).
Explore position #801Provenance
Mined from the project's engine self-play games.
Pack 013 · SP-801
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