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Ponderchess / Glossary

Discovered attack in chess

A discovered attack happens when one piece moves out of the way and uncovers an attack by a piece standing behind it. Because the moving piece can make a threat of its own, the opponent often faces two threats at once. When the uncovered attack is on the king, it is a discovered check.

White to move. The bishop on d3 stands between the rook on d1 and the black queen on d6. Bxh7+ takes a pawn with check and uncovers the rook's attack on the queen. Black must answer the check first, by Kxh7 or Kh8, and then Rxd6 wins the queen. Even after Black recaptures the rook, White is well ahead.1.Bxh7+ Kxh7 2.Rxd6

How a discovered attack works

Two pieces of the same colour stand on one line: a bishop, rook or queen behind, and any piece in front blocking it. When the front piece moves, the line opens and the piece behind attacks whatever is at the far end.

The power lies in the double threat. The moving piece can capture something, give check or attack another target, while the uncovered piece makes its own attack. The opponent usually has time to answer only one.

Discovered check

If the uncovered piece attacks the king, the opponent must deal with the check before anything else. That gives the moving piece complete freedom: it can capture a defended piece, attack the queen or even stand where it can be taken, because the reply has to answer the check. If the moving piece gives check too, the result is a double check.

Typical patterns

A bishop on d3 in front of a rook or queen on the d-file can capture on h7 with check, uncovering an attack down the file on a queen on d6 or d8. A knight that leaves the e-file can uncover a rook on e1 against a king or queen on the e-file. Repeated discovered checks by a rook and bishop form the windmill.

How to spot and defend against them

Look along every line from your bishops, rooks and queen, even when your own piece is in the way. If an enemy king or queen stands at the end, ask where the blocking piece could go with a threat. When defending, treat a line from an enemy line piece to your king or queen as dangerous even while it is blocked, and step off it in good time.

Common mistakes

  • Leaving the queen on a file or diagonal behind an enemy piece that can move away with check.
  • Moving the front piece to a quiet square when it could move with a threat of its own.

Questions about discovered attack

What is the difference between a discovered attack and a discovered check?

A discovered check is a discovered attack in which the uncovered piece attacks the king. It is the most forcing kind, because the check must be answered at once.

Is a discovered attack a fork?

Not quite. A fork is one piece attacking two targets. A discovered attack is a double attack by two pieces, the one that moves and the one it uncovers.

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