Mate in 3: rook to a6 (b6)
c9-09013naming 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.
Difficulty 2210 ShuffleRating — expert level — few solve it at first try.
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.
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 a2, queen e3, rook b6, bishop c2 a5, pawn g2 h3 b4 e4 d5.
Black: king a7, queen e7, rook f1, bishop d7, knight g4, pawn c4 h4 g6 b7.
10 white and 9 black pieces are on the board; the puzzle position arises after move 35.
The position in numbers
White are ahead by 1 points of material (25 against 24; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on a2, the black king on a7.
It is White to move on move 35, with 37 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 4. Files fully open (no pawns of either colour): a, f — natural highways for the rooks and queen. Half-open for White: c.
White hold the bishop pair, an edge in open lines. 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
35. Ra6+ Kb8 36. Qa7+ Kc8 37. Qa8#
Why it works
- Great move! rook to a6 keeps the pressure (#2).
- Well found: queen to a7 (#1).
- Precise: queen to a8 is the top choice (#).
- The line ends in a forced mate in 3.
- If instead Kb8, then Qa7+ and you stay on top.
Move by move
- 35. Ra6+ — rook to a6 with check
- Kb8 — king to b8
- 36. Qa7+ — queen to a7 with check
- Kc8 — king to c8
- 37. Qa8# — queen to a8 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.
Relative pin
A piece shields a more valuable one behind it — moving it loses material.
In a relative pin the piece shields not its king but something valuable behind it, usually the queen. Moving is legal but costly, because the piece behind falls. Look for three units on one line: your long-range piece, a cheaper enemy piece, and an expensive one hiding behind. Beware the classic trap — a relatively pinned piece can still move with check or a bigger threat, so verify before you cash in.
Counter-strike
Don't defend — answer the threat with a bigger one.
The counter-strike: instead of defending against the threat, you answer with a bigger threat of your own. While your opponent grabs a pawn, you deliver mate — the arithmetic favors you. Look for a counter when direct defenses fail: do you have a check, an attack on the queen, a mating threat? The beginner's error is meeting every threat with a reflexive defense without checking the counterattacking resources first.
About this position
These pieces come from starting position #712.
SP-712 · BastionGuard — Both knights begin inside the board while the king stands on c or f; a position and its mirror twin share this family.
The king starts on c1, the rooks on a1 and h1, the queen on d1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
The bishops stand on b1 and e1; their long diagonals reach h7 and a5 once the c- and d-pawns step aside.
One second-rank pawn starts with no defender at all: g2.
The setup belongs to the BastionGuard family; read right to left it becomes position 445.
The engine's main line opens with c4.
Morozov Balance Index: 37 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +30 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #712Provenance
Mined from the project's engine self-play games.
Pack 015 · SP-712
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