A double check is a check from two pieces at once, made by a discovered check in which the moving piece also gives check. The only legal answer is a king move.
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No single move can block or capture two checkers, so the king has to move. If it has no safe square, a double check is mate even when either checking piece could be captured.
How to do it
- 1Find a discovered check: your piece in front of a bishop, rook or queen aimed at the king.
- 2Move the front piece to a square where it gives check too.
- 3Count the king's escape squares. If there are none, it is mate.
For your level
The checking pieces may stand where they could be captured. It does not matter, because only a king move is legal.
Common mistakes
- Giving a double check without first counting the king's escape squares.
- Rejecting a double check because the moving piece is unprotected. Only the king can take it.
Questions
- Can you block a double check?
- No. A block stops one line of attack and leaves the other, and a capture removes only one checker. The only legal answer is to move the king.
- Can the king capture a piece giving double check?
- Yes, if that piece stands next to the king and the square is not attacked by anything else. Capturing with the king is a king move, so it is legal.