A discovered attack happens when one piece moves out of the way of another, revealing an attack along a rank, file, or diagonal. The moving piece can create its own threat while the piece behind it attacks something else.
Read both moves in one
Imagine a bishop on b2, a friendly knight on c3, and a target farther along the b2–h8 diagonal. Moving the knight may uncover the bishop’s attack. The knight’s destination matters: can it attack a queen, capture a pawn, or give check at the same time?
The strongest discoveries often combine a newly opened attack with an immediate threat from the moving piece. The defender may have too many problems to solve in one turn.
Distinguish discovered check and double check
If the uncovered piece attacks the king, the move gives discovered check. If the moving piece also checks, it is double check. In double check, the defender must move the king; capturing or blocking only one checker does not remove the other check.
That does not mean every double check wins. A safe king escape may leave the attacking side with insufficient compensation. Calculate the destination, not only the dramatic first move.
Look for batteries
A battery is an arrangement of pieces ready to cooperate along a line. When studying a game, identify the line before the blocker moves. Then explain why that precise moment makes the discovery effective: the target arrived, a defender left, or the king lost an escape square.
Give the moving piece a second job
Read all 3 moves and their reasons
- 1. Nd5+ Moving the knight opens the bishop’s check on h8 and attacks the rook on f4.
- 1… Kg8 Black steps out of the diagonal. This is one legal reply, not the only reply.
- 2. Nxf4 White takes the rook. Also check the alternative 1…Rf6: 2.Nxf6 wins that rook too.
The bishop on b2 already points toward h8, but its own knight on c3 blocks the diagonal. A random knight move would uncover check. Nd5+ does more: from d5, the knight attacks the rook on f4. One move creates a bishop check and a knight threat against a different target.
The displayed …Kg8 answers the check but permits Nxf4. Black has another idea: …Rf6, placing the rook on the bishop’s diagonal to block the check. White can then play Nxf6, taking that rook instead. This capture does not give check: the white knight on f6 now blocks its own bishop’s diagonal. Updating the board after every move matters more than remembering the label “discovered check.”
The position has very little material so the mechanism is easy to see. Winning the rook does not make the first move a double check: the knight on d5 does not itself attack h8. Only the bishop is checking.
Look before the battery is ready
In a full game, the bishop may need several moves to reach b2 and the enemy king may not yet be on h8. Those preparatory details determine whether the pattern is a threat or merely a possibility.
When a piece moves off a long line, inspect the whole line it vacated. Beginners often look only at the moving piece’s new attacks and miss the rook, bishop, or queen it has uncovered. After an opponent’s knight move, ask what became visible behind it.
Your turn
Pause. Think. Explain.
Your knight moves with check and uncovers a bishop check at the same time. Can the defender answer by blocking only the bishop's diagonal?
Reveal the explanation
No. The knight would still be checking the king. A double check requires a legal king move that escapes both attacks.
Take it to the board
One idea. A whole game to find it in.
Choose a complete game, hide the next move, and explain your candidate before you reveal it.
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