Pin Puzzles: Freeze a Piece and Win It

A pin happens when a bishop, rook or queen attacks an enemy piece that cannot move without exposing something more valuable behind it. The front piece is stuck. It still stands on the board, but it has stopped doing its job, and that is often all you need to win material or deliver mate.

Pins are quieter than forks. They rarely win something on the spot. Instead, they create a weakness you can attack again and again until the position cracks.

Two kinds of pin

An absolute pin is a pin against the king. The pinned piece is legally not allowed to move off the line, because that would put its own king in check. A white bishop on b5 pinning a black knight on c6 to the king on e8 is a classic case: as long as d7 stays empty, that knight cannot move at all.

A relative pin is a pin against anything else, usually the queen or a rook. A bishop on g5 hitting a knight on f6 with the queen behind on d8 is the standard example. The knight may legally move, but doing so hands over the queen. Relative pins can be broken, sometimes with a counterattack, so they need a little more calculation.

How to recognize a pin in a puzzle

Look for lines. Draw imaginary rays from your bishops, rooks and queen through the first enemy piece they meet and ask what stands behind it. Useful cues:

• The enemy king and queen share a file, rank or diagonal.
• A piece is defending something important but sits in front of a more valuable piece.
• An enemy piece is pinned and attacked once, and you can add a second attacker, often a pawn.
• A pinned piece appears to protect a square, but in reality it cannot move to use that protection.

That last cue is a favorite in puzzles. A pinned knight that seems to guard a square is an illusion, and the solution often punishes the player who trusts it.

Exploiting a pin step by step

Once a piece is pinned, the usual plan is simple: attack it with more pieces than can defend it, ideally with something cheap. A pawn advancing onto a pinned piece is especially brutal, because the piece cannot run. Another strong idea is to attack the pinned piece’s defenders, or to use the moment while it is frozen to strike somewhere it would normally cover.

Watch out for the fact that a pinned piece still gives check and still controls squares for the purposes of the enemy king. A knight pinned against its own king can still prevent your king from stepping next to it.

Mistakes to avoid

• Overestimating a relative pin. Your opponent may break it with a move that creates a bigger threat, such as a check or an attack on your queen.
• Pinning without follow-up. A pin with nothing to attack the pinned piece is just a nuisance. Ask what your second move is.
• Walking into pins. Before castling or moving your queen, check whether any of your pieces would end up in front of something valuable on an open line.

Practical tips

1. Scan for king and queen on the same line. It takes seconds and finds a surprising number of tactics.
2. Add attackers, don’t trade them. While the pin holds, keep pressure on the frozen piece instead of capturing too early.
3. Unpin before it hurts. When you are the one being pinned, stepping the king or queen off the line one move early often saves the whole game.

Springer would add one more piece of advice: a knight in front of its own king is the most common pinned piece of all, so learn to see that shape instantly.