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Attack on the uncastled king: bishop to b6 (d4·6)

Shuffle Rating 1630Theme: 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.

Mate in 3: a forced sequence that ends in checkmate.

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

Difficulty 1630 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.

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.

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 g1, queen f2, rook b1 a3, bishop d4, knight d3 d5, pawn c2 g2 f3 h3 c4 e4.

Black: king d8, queen b6, rook a8 e8, knight e7 c8, pawn a5 f6 d7 g7 h7.

13 white and 11 black pieces are on the board; the puzzle position arises after move 29.

The position in numbers

White are ahead by 4 points of material (34 against 30; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.

The white king stands on g1, the black king on d8.

It is White to move on move 29, with 56 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): b — natural highways for the rooks and queen. Half-open for White: a, d.

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

29. Bxb6+ Nxb6 30. Qxb6+ Kc8 31. Qc7#

Why it works

  • Great move! bishop to b6 keeps the pressure (#2).
  • Well found: queen to b6 (#1).
  • Precise: queen to c7 is the top choice (#).
  • The line ends in a forced mate in 3.
  • If instead Nxb6, then Qxb6+ and you win the queen.

Move by move

  • 29. Bxb6+ — bishop to b6 (capture) with check
  • Nxb6 — knight to b6 (capture)
  • 30. Qxb6+ — queen to b6 (capture) with check
  • Kc8 — king to c8
  • 31. Qc7# — queen to c7 and it is checkmate

Types in this puzzle

Ladder mate

Two heavy pieces climb line by line, cutting off every retreat.

The ladder mate uses two heavy pieces climbing rung by rung: one cuts the king off along a line, the other checks on the next line, driving him toward the edge. It is the classic two-rook technique — check, the king retreats one rank, the other rook checks, until mate on the last rank. The only danger is the king creeping close enough to attack one of your rooks. If it does, simply slide that rook to the far side of the same line.

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.

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 #642.

SP-642 · ThroneScout — King on a central file (d/e) with a knight starting on the rim (a/h).

The king starts on d1, the rooks on b1 and e1, the queen on g1.

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.

A bishop starts in the corner on a1: it has a single diagonal, which the b-pawn unlocks, running out to h8.

The pawn on c2, d2 is defended by the king alone — the same soft spot f2 is in the classical setup.

The setup belongs to the ThroneScout family; read right to left it becomes position 215.

The engine's main line opens with f4.

Morozov Balance Index: 75 of 100 — class B — balanced. Engine evaluation of the starting position: +19 centipawns for White (depth 48, 400 000 000 nodes).

Explore position #642

Provenance

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

Pack 012 · SP-642

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