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Attack on the uncastled king: bishop to b7 (a6·3)

Shuffle Rating 920Theme: Chess960 twist: use the unusual starting setup of the pieces.
White to move — find the best continuation

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The tactical motive

Chess960 twist: use the unusual starting setup of the pieces.

An opening trap from this Chess960 starting position.

Uncastled king: the enemy king is stuck in the centre — punish it before it castles.

Winning tactic: there is a move that gains a decisive advantage — find it.

Difficulty 920 ShuffleRating — for beginners taking their first steps in Chess960 tactics.

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.

Early Chess960 traps punish natural but careless development. Look for a forcing move that exploits a piece the opponent has just placed on a poor square — a fork, a pin or a threat that wins material before either side is fully developed.

An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.

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 c1, queen g1, rook b1 e1, bishop a1 a6, knight h1 e3, pawn a2 b2 c2 d2 g2 h2 e4 f4.

Black: king c8, queen g8, rook b8 e8, bishop b7 f8, knight e5 h8, pawn b6 a7 c7 d7 e7 f7 g7 h7.

16 white and 16 black pieces are on the board; the puzzle position arises after move 5.

The position in numbers

Material is level — 39 points of pieces on each side (pawn = 1, knight and bishop = 3, rook = 5, queen = 9).

The white king stands on c1, the black king on c8.

It is White to move on move 5, with 35 legal replies to weigh — only the line that keeps the advantage solves the puzzle.

White keeps 8 pawns, Black 8. No file is fully open, so the heavy pieces have to be pried in.

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

5. Bxb7+ Kxb7 6. fxe5

Why it works

  • Great move! bishop to b7 keeps the pressure (+5.1).
  • Well found: pawn to e5 (+4.8).
  • You win a piece — the bishop.
  • If instead Kxb7, then fxe5 and you win the bishop.

Move by move

  • 5. Bxb7+ — bishop to b7 (capture) with check
  • Kxb7 — king to b7 (capture)
  • 6. fxe5 — pawn to e5 (capture)

Types in this puzzle

King in the center

The king starts in the middle — and the storm reaches it first.

King in the center: in Chess960 the monarch may start on the d- or e-file, right in the line of fire, and the attack can reach him before he ever castles. The signs: the enemy king still sits on its central starting square while the files toward it are opening. Play to rip the center open — a pawn sacrifice usually pays off here. And if it is your king in the middle, castle at the very first opportunity.

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.

Uncastled king

The king lingered in the middle — punish the delay.

Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.

About this position

These pieces come from starting position #834.

SP-834 · BastionScout — King off-centre on c or f with a knight starting on the rim (a/h).

The king starts on c1, the rooks on b1 and e1, the queen on g1.

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 119.

The engine's main line opens with f4.

Morozov Balance Index: 89 of 100 — class A — most balanced. Engine evaluation of the starting position: +14 centipawns for White (depth 45, 400 000 000 nodes).

Explore position #834

Provenance

Mined from the project's engine self-play games.

Verified by Stockfish at depth 20+.

Solution forcedness confirmed (verified).

Pack 004 · SP-834

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