The discovered attack: one piece moves, another strikes
In a discovered attack, a piece steps out of the way and uncovers an attack by the rook, bishop or queen behind it. When the piece that moves makes a threat too, two threats arrive with one move; in a double check, the strongest form, the king has to move.
What a discovered attack is
Rooks, bishops and queens attack along lines, and any piece standing on such a line blocks it, even one of your own. Move that piece, and the piece behind it now attacks whatever stands at the other end of the line: that is a discovered attack. It becomes dangerous when the piece that moves makes a threat of its own, a capture, a check or an attack on something else. Your opponent then faces two threats with a single move to answer them.
In the Lichess puzzle database (6.2 million puzzles), 5.1% of the puzzles are tagged as discovered attacks and 0.5% as double checks. Discovered attacks are also one of the ten themes of 300 Chess Puzzles, with thirty puzzles from about 600 to 1800 Elo. Three terms are worth knowing:
- Discovered attack: the uncovered piece attacks an enemy piece.
- Discovered check: the uncovered piece gives check, so the piece that moved is free to go anywhere.
- Double check: the piece that moved and the uncovered piece both give check, and only a king move can answer it.
Three signals of a discovered attack
- One of your pieces stands between your rook, bishop or queen and an enemy target: a loose piece, the queen or the king.
- That piece can move with a threat of its own: a capture, a check or an attack on a second target.
- The target is the king. Then it is a discovered check, the strongest kind: the moving piece can go anywhere, even to a square where it can be taken.
The difficulty is that the attack stays invisible until the piece moves. We look at what each piece attacks, not at what it hides. So look along the lines of your rooks, bishops and queen, and at the pieces standing in front of them, your own included.
Two puzzles from real games
A bishop moves with check
The black bishop is in the way of its own rook, so 1…Bxf2+ takes a pawn with check and, by leaving d4, uncovers the rook on d7, which now attacks the rook on d1. White must answer the check first: after 2.Kxf2, 2…Rxd1 wins the rook, and the other king moves change nothing. The check matters: after a quiet bishop move, the open file would work both ways, and White would take the rook on d7 first.
A knight moves with check
Here the knight blocks the f-file. 1.Nh5+ moves it with check, and the rook on f1 now attacks the queen. Black has to deal with the check, for example with 1…Kg6, and 2.Rxf5 takes the queen. The king can take the rook back, but Black has given the queen for a rook.
The tempting move is the other knight check, 1.Nxe6+?. It uncovers the rook too, but the queen answers 1…Qxe6!: it takes the knight that gave check and leaves the f-file at the same time. Now Black is the one who is winning.
Before a discovered attack, check that your opponent cannot meet both threats with one move, for example by taking the piece that moved.
Discovered check and double check
When the uncovered piece attacks the king, the piece that moves can go anywhere, because the check must be answered first. In a worked example from our puzzle book, a white pawn on d5 blocks a bishop on b3 aimed at the king on g8. 1.d6+ opens the diagonal with check and attacks a bishop on e7 at the same time; after 1…Kh8, 2.dxe7 wins it.
A double check goes one step further: the piece that moves gives check too. No single move can take both checking pieces or block both lines, so the king must move, and if it has no safe square, it is mate. A trap of the Scotch Game, one of the ten in The Scotch Game in Twelve Lessons, shows it on move nine: 1.e4 e5 2.Nf3 Nc6 3.d4 d5 4.Nc3 dxe4 5.Nxe4 Bg4 6.Be2 exd4 7.Nxd4 Bxe2 8.Qxe2. The knight on d4 has no defender, and Black takes it with 8…Qxd4??.
9.Nf6+! checks from f6, and by leaving e4 the knight uncovers the queen on the e-file. Two checks at once: the king must move, 9…Kd8 is its only square, and 10.Qe8# is mate, the queen protected by the knight. Taking with the knight instead, 8…Nxd4??, loses even faster to 9.Nf6#. You will find this trap with two others in our article on Scotch Game traps.
How to train your eye
Before each move, look along the lines of your rooks, bishops and queen. If one of your own pieces stands in front of them, ask where it could go with a threat of its own, and what the line would hit once it opens. Do the same for your opponent: an enemy rook or bishop aimed at your king or queen through a single piece is a warning.
Then solve discovered attacks on paper, writing the whole line before you check the answer. The two puzzles above are free with eighteen others in our Lichess study. Our article on pins and skewers covers the other line tactics, and each Knight’s Notebook brings sixty puzzles at your level every month.