A discovered attack happens when a piece moves and uncovers an attack by a bishop, rook or queen that was standing behind it. The moving piece is free to go anywhere — even to give up itself — because the real threat comes from the piece it uncovered. That makes discovered attacks uniquely dangerous: the move you see is not the move that hurts you.
The strongest version is discovered check, where the uncovered piece checks the king. The defender must answer the check, so the moving piece gets a free move to capture something, promote, or land on a crushing square. A double check — where the moving piece also gives check — is stronger still: the king itself must move, because no block or capture can answer two checks at once.
How to spot it
- Your bishop, rook or queen aiming at something valuable, with one of your own pieces parked in front of it — that parked piece is loaded.
- An enemy line piece with its own piece in front pointing at your king or queen: when the front piece jumps, what does it uncover?
- A battery on a file or diagonal (two line pieces in a row) — the front one can move with double effect.
Using it — and stopping it
To use a discovered attack, choose the moving piece's destination as if it had a free move: the best square it can reach, not just a safe one. Checks and captures by the moving piece are strongest because the defender is busy answering the uncovered attack. To defend, watch batteries: when an enemy line piece and a front piece both point at you, treat the front piece as if it were already gone and ask what the position looks like then.
Common mistakes
- Judging a move only by where the piece lands, and missing the line it opened behind it.
- Blocking a discovered check by capturing the moving piece — legal only if the capture also answers the uncovered check. Against double check it never works: the king must move.
- Parking your own piece in front of your line piece aimlessly. Every piece in front of a battery is a future discovered attack; park it somewhere its jump does damage.
The piece that moves is the decoy; the piece behind it is the weapon. The puzzles below put you on both ends of that trick.