Trapped piece

A trapped piece has no safe square or practical route of escape. Its movement may be restricted by friendly pieces, the edge of the board, or squares controlled by the opponent. Queens, rooks, bishops, and knights can all be trapped. Even when capture is not immediate, the piece may be unable to take a useful part in the game.

Functional exclusion

Protected and out of play

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The king on b8 protects the bishop, while b7-b6 is immobile because the pawn on b6 cannot advance onto b5.

A sealed diagonal

The bishop on a8 is protected by the king on b8, but b7 and b6 form an immobile chain fixed by the white pawn on b5. The bishop's only diagonal stays closed.

1. The king on b8 protects the bishop, while b7-b6 is immobile because the pawn on b6 cannot advance onto b5.
2. The bishop's only diagonal ends immediately on b7, occupied by a friendly pawn that cannot clear the line.

The tactical motif often develops in two stages. First, the escape squares are reduced or controlled. Then the piece is attacked with tempo, meaning the attacker improves the position while forcing a response. The victim may sometimes open an exit through a sacrifice, exchange itself for another piece, or create a more urgent threat.

Reachable capture

Closing two routes with one move

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The a7-b6-c5 diagonal remains open, but b8 is controlled by the white king.

The corridor is still open

The bishop on a7 can still use the a7-b6-c5 diagonal, while b8 is controlled by the white king on c7.

1. The a7-b6-c5 diagonal remains open, but b8 is controlled by the white king.

To prove that a piece is truly trapped, check every legal move and every intermediate move that creates a threat before attempting the retreat. A piece that looks enclosed may escape by giving check, capturing a defender, or exploiting counterplay, active play that creates a more urgent problem for the opponent.

Escape resource

Check changes the diagnosis

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Nxc7+

The queen controls b6 and the bishop protects the queen on c7; both exits appear covered.

Two deceptive squares

The knight on a8 has only b6 and c7. The white queen controls b6, while c7 is occupied by that queen and backed by the bishop on f4.

1. The queen controls b6 and the bishop protects the queen on c7; both exits appear covered.