What is a discovered attack in chess?
Updated
A discovered attack happens when you move one piece out of the way and uncover an attack by a bishop, rook or queen behind it. The piece that moved can make a threat of its own, so your opponent faces two threats from one move.
How a discovered attack works
You need two pieces of your own on one line, with an enemy target at the far end. The front piece blocks the attack until it moves. In the diagram below, the white bishop on e4 stands between the rook on e1 and the black queen on e7.
Bxh7+ takes a pawn with check and opens the e-file. Black must answer the check, so the queen has no time to move, and Rxe7 wins her next. If the king takes the bishop, White has given 3 points for 9 and a pawn. If the king steps to f8 instead, it can recapture with Kxe7, but White has still swapped a rook for a queen and kept the bishop.
In this example the moving piece gives the check. When the piece behind it attacks the king, that is called adiscovered check.
Without a check
The moving piece doesn't have to give check. It just has to make a threat that matters. Here the pawn on d4 blocks the bishop on b2. After d5 the pawn attacks the knight on c6, and the bishop attacks the rook on h8.
Black can't deal with both. If the rook moves, dxc6 wins the knight. If the knight moves,Bxh8 wins the rook. Blocking doesn't help either: f6 leaves the knight to be taken, and Ne5 just puts the knight where Bxe5 can take it.
Double check
If the moving piece also gives check, the king is attacked by two pieces at once. That is a double check, and it is the strongest version, because the only legal reply is a king move. You can't block two lines with one move, and capturing one attacker leaves the other.
Here Black's knight could block one line and the h-pawn could capture the bishop, but neither is legal. The king has to step to d8 or f8, and Re8# is checkmate either way.
Try it: find the discovered attack
White to move. Your knight on d5 is selected, and it blocks your bishop's line to the queen on b7. The knight needs to move with check. Two jumps give check, but only one works.
Show answer
Nf6+. The knight checks the king and uncovers the bishop on the queen. Black has to answer the check, so Bxb7 wins the queen next, even if the g-pawn takes the knight. The other check, Nc7+, fails to Qxc7.
How to spot a discovered attack
- Find your lined-up pieces. Look for a bishop, rook or queen with just one of your own pieces in front of it.
- See what is at the far end. A king, a queen or an undefended piece is worth a closer look.
- Ask what the front piece can do. The best move is usually a check or a capture, because it gives your opponent no time to deal with the piece behind.
How to defend against a discovered attack
Treat an enemy bishop, rook or queen as if the piece in front of it were not there. If that imaginary line reaches your king, queen or an undefended piece, you have a problem to solve now, while you still have a free move.
- Step off the line. Move the target before the front piece moves.
- Guard the target. A defended piece can be recaptured, so the attack may win less.
Compare this position with the first example. The queen is on d7, not e7, so the e-file leads nowhere.
Like a fork, a discovered attack makes two threats with one move. For attacks along a single line, see the pin and the skewer.
Questions people ask
- What is the difference between a discovered attack and a discovered check?
- A discovered check is a discovered attack on the king. A discovered attack can target any piece.
- Which pieces can make a discovered attack?
- The piece that uncovers the line can be any piece, even a pawn or the king. The piece behind it must be a bishop, rook or queen, because only they attack along lines.
- How do you get out of a double check?
- Only by moving the king. Blocking or capturing can deal with one of the checking pieces, but never both.