Winning blow: bishop to a4 (b5)
c9-21415naming 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 1060 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 e1, queen d1, rook a1 g1, bishop b5, knight e6, pawn g2 a3 e4 f4 h4.
Black: king b6, rook a4 h8, bishop e7 f7, knight b8 c8, pawn b2 c3 c6 f6 h7.
11 white and 12 black pieces are on the board; the puzzle position arises after move 21.
The position in numbers
White are ahead by 3 points of material (30 against 27; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on e1, the black king on b6.
It is White to move on move 21, with 43 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 5 pawns, Black 5. Files fully open (no pawns of either colour): d — natural highways for the rooks and queen. Half-open for White: b, c.
Black 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
21. Bxa4 bxa1=Q 22. Qxa1 Bxe6 23. Qxc3
Why it works
- Great move! bishop to a4 keeps the pressure (+2.3).
- Well found: queen to a1 (+2.4).
- Precise: queen to c3 is the top choice (+2.2).
- You reach a winning position (+2.2).
- If instead bxa1=Q, then Qxa1 and you stay on top.
Move by move
- 21. Bxa4 — bishop to a4 (capture)
- bxa1=Q — pawn to a1 (capture)
- 22. Qxa1 — queen to a1 (capture)
- Bxe6 — bishop to e6 (capture)
- 23. Qxc3 — queen to c3 (capture)
Types in this puzzle
Remove the defender
Capture the guard first — then take what it protected.
Removing the defender is the straightforward plan: capture the guard first, then take what it guarded. Unlike deflection, the defender is not lured away — it is traded off or destroyed on the spot. Stare at the target you crave and ask who defends it, and whether that defender can be profitably eaten. Count the whole capture sequence, not just the first move — the trade must pay off at the end.
About this position
These pieces come from starting position #446.
SP-446 · ThroneGuard — The king starts in the middle of the back rank, on d or e, and neither knight begins in a corner.
The king starts on e1, the rooks on a1 and h1, the queen on d1.
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.
The bishops stand on f1 and g1; their long diagonals reach a6 and a7 once the e- and f-pawns step aside.
One second-rank pawn starts with no defender at all: b2.
The setup belongs to the ThroneGuard family; read right to left it becomes position 708.
The engine's main line opens with e4, putting a pawn straight into the centre.
Morozov Balance Index: 65 of 100 — class B — balanced. Engine evaluation of the starting position: +22 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #446Provenance
Mined from the project's engine self-play games.
Pack 007 · SP-446
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