A discovered attack in chess is a move where one piece steps off a line and uncovers an attack by a bishop, rook or queen standing behind it. The piece that moves can make its own threat at the same time, so one move creates two attacks, and your opponent can usually answer only one. When the uncovered attack hits the king, it is a discovered check, the strongest version, because the opponent must deal with the check before anything else.
A discovered check, step by step
White's rook on e1 is aimed at the black king on e8, but White's own knight on e5 blocks the file. The knight is the key: wherever it goes, the rook gives check.
1q2k3/5ppp/8/4N3/8/8/5PPP/4R1K1 w - - 0 1
Open this position in the analysis board →
1.Nc6+ uncovers check from the rook and attacks the queen on b8 with the knight. Black has exactly three legal moves: Kf8, Kd7 and Qe5. Blocking with 1...Qe5 loses the queen to 2.Rxe5+, and either king move allows 2.Nxb8. Stockfish 17.1 at depth 18 picks 1.Nc6+ and rates White about +6.8. No other White move gets more than a draw-ish +0.15.
The two pieces have different jobs. The moving piece (here the knight) makes the second threat. The line piece behind it (the rook) delivers the attack you uncover.
Which pieces make discovered attacks?
We checked all 37 discovered attack puzzles in our trainer, which come from the Lichess puzzle database. For each one we found the first solution move that opens a new attack by a bishop, rook or queen on an enemy piece, and recorded which piece moved and which piece was uncovered.
| Moving piece | Puzzles | Share |
|---|---|---|
| Knight | 15 | 41% |
| Bishop | 7 | 19% |
| Pawn | 6 | 16% |
| Rook | 5 | 14% |
| Queen | 4 | 11% |
| Uncovered piece | Puzzles | Share |
|---|---|---|
| Rook | 16 | 43% |
| Bishop | 12 | 32% |
| Queen | 9 | 24% |
Method: we replayed each puzzle with the chess.js move generator and compared the bishop, rook and queen attacks before and after each solution move, ignoring attacks made by the piece that moved. The key move gave check in 31 of the 37 puzzles (84%), and Lichess tags 13 of them as discovered checks. Ratings run from 789 to 2330, with a median of 1514, and all but one solution take two or three moves.
The lesson: a knight in front of a rook or bishop is the setup to look for, and the discovered attack is usually backed by a check.
The Petrov trap: a discovered check on move five
This opening trap catches beginners who copy White's moves without thinking. Black takes the e4 pawn, then retreats the knight and leaves the queen on d8 exposed.
Start
After 4.Qe2 the white queen and the black king stand on the same e-file, with only White's knight on e5 between them. 5.Nc6+ is a discovered check from the queen, and the knight attacks the black queen on d8. Black has exactly three legal moves, 5...Qe7, 5...Be7 and 5...Ne4, and none of them saves the queen. Stockfish 17.1 at depth 18 rates the position about −4.8 for Black after the best reply, 5...Qe7 6.Nxe7.
The correct defence is 4...Qe7, which blocks the file before White can uncover it. Stockfish rates that line only about +0.6 for White.
When a discovered attack does not work
A discovered attack fails when the piece you uncover is loose and the opponent can take it first. Here White's rook on e1 attacks the queen on e7 as soon as the knight moves, but the rook is undefended and White's king sits on a weak back rank.
6k1/4qppp/8/8/4N3/8/5PPP/4R2K w - - 0 1
Open the loose-rook position →
A careless knight move such as 1.Nc5?? is met by 1...Qxe1#, checkmate. Black's queen was the target, but it was also attacking the rook along the same file. Only 1.Nf6+ works: the knight check stops Black from capturing the rook. Black cannot play 1...Qxf6 because 2.Re8# is mate, so after 1...Kf8 2.Nxh7+ Ke8 3.Rxe7+ White wins the queen. Stockfish 17.1 at depth 20 rates 1.Nf6+ about +5.4 and the next best move, which is not a knight move at all, about −0.1.
The rule: if the target can capture the piece you uncover, your moving piece must give check or make an equally big threat.
Discovered check and double check
A discovered check is a discovered attack where the uncovered piece checks the king. A double check is a discovered check where the moving piece also gives check, so the king is attacked by two pieces at once. A double check can never be blocked or answered by capturing, because no single move stops both checkers. The king must move. That is why double checks so often end in mate.
How to spot a discovered attack in your games
Run this check whenever one of your pieces stands between your own bishop, rook or queen and an enemy piece:
- Find the battery. Look for your line piece aimed at the king, the queen or a loose piece, with exactly one of your pieces in the way.
- Find a threat for the front piece. The moving piece should check, capture, or attack something valuable. A quiet move wastes the discovery.
- Check the counter-attack. Can the target capture your uncovered piece, or give check? If so, you need a check with the front piece.
- Prefer double check. When the moving piece can also give check, the king must move, and mating patterns appear.
And the defensive view: when an enemy piece stands between your king or queen and a hostile rook, bishop or queen, step off that line, or block it with a second piece, before the front piece moves. That is exactly what 4...Qe7 does in the Petrov.
Practice: Discovered attack
All 37 discovered attack puzzles →Frequently asked questions
What is a discovered check?
A discovered check happens when you move one piece and uncover a check from a bishop, rook or queen behind it. The moving piece is free to attack something else, often the queen, while your opponent is forced to answer the check.
What is a double check?
A double check is a move that checks the king with two pieces at once, usually a discovered check where the moving piece also gives check. Since you cannot block or capture two checkers with one move, the only legal reply is a king move.
How do you defend against a discovered attack?
Break the line before it opens. Move your king or queen off the line the enemy piece is aiming down, block it with a defended piece, or attack the front piece so it cannot move freely. If the attack has already happened and there is no check, save the more valuable piece, or capture the uncovered attacker if it is loose.
What is the difference between a discovered attack and a pin?
In a pin, your piece on a line stops an enemy piece from moving. In a discovered attack, your own piece stands in the way and moves off the line to unleash the attack. Both rely on line pieces, like the skewer, while a fork uses one piece to attack two targets directly.
Ready for practice? The discovered attack puzzles page has all 37 discovered attack puzzles, from beginner to advanced, and the analysis board lets you test any discovered check you find in your own games.