Winning blow: pawn to a6 (a5)
c9-09376naming 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.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1390 ShuffleRating — club-player level.
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.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
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 b3, rook d5, knight d3, pawn a5 c5 e5 b6.
Black: king c8, rook h2, bishop e3, pawn g3 d4 g5 d7.
7 white and 7 black pieces are on the board; the puzzle position arises after move 39.
The position in numbers
Material is level — 12 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).
The white king stands on b3, the black king on c8.
It is White to move on move 39, with 17 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 4. Files fully open (no pawns of either colour): f, h — natural highways for the rooks and queen. Half-open for White: d, g.
The White king has 4 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
39. a6 Rh1 40. b7+ Kc7 41. Rxd7+ Kxd7 42. b8=Q
Why it works
- Great move! pawn to a6 keeps the pressure (+5.9).
- Spot on — pawn to b7 (+5.1).
- Precise: rook to d7 is the top choice (+6.4).
- Sensible development: pawn to b8.
- You win a piece — the pawn.
- If instead Rh1, then b7+ and you stay on top.
Move by move
- 39. a6 — pawn to a6
- Rh1 — rook to h1
- 40. b7+ — pawn to b7 with check
- Kc7 — king to c7
- 41. Rxd7+ — rook to d7 (capture) with check
- Kxd7 — king to d7 (capture)
- 42. b8=Q — pawn to b8
Types in this puzzle
Promotion
The pawn reaches the last rank and becomes a queen — decisively.
Promotion turns a pawn on the last rank into a queen and rewrites the evaluation on the spot. In tactics the passer rarely walks in for free — usually a sacrifice clears its path. Count the tempi: how many moves does the pawn need, and can the defender stop it in time? And watch the promotion square itself — it must be out of enemy reach or won by force in your combination.
Promotion race
Both sides push passers — win the race by a tempo.
A promotion race is a sprint between two passed pawns: both sides push toward the last rank, and victory goes to whoever queens first or queens with check. You will recognize it when both players have far-advanced passers that neither king can catch. Count the tempi literally, move by move, all the way to promotion. The classic mistake is spending a tempo on a "useful" move — in a race, almost any non-pawn move loses.
Quiet move
No check, no capture — yet this modest move decides the game.
A quiet move gives no check and takes nothing — yet it decides the game by creating an unstoppable threat or stealing the king's last square. This is the hardest class of moves: the eye hunts for loud blows while a modest shift does the winning. The clue: every forcing try runs into a defense, so seek the move that strengthens the threat or takes squares away. Train yourself to ask: what if I neither capture nor check, but quietly improve?
About this position
These pieces come from starting position #895.
SP-895 · BastionGuard — The king starts one file off-centre, on c or f, with neither knight in a corner.
The king starts on c1, the rooks on a1 and d1, the queen on b1.
The king already stands on c1, so castling long moves only the rook, from a1 to d1.
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: e2.
The setup belongs to the BastionGuard family; read right to left it becomes position 64.
The engine's main line opens with g4.
Morozov Balance Index: 11 of 100 — class D — largest edge. Engine evaluation of the starting position: +42 centipawns for White (depth 41, 400 000 000 nodes).
Explore position #895Provenance
Mined from the project's engine self-play games.
Pack 010 · SP-895
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