Double Check in Chess

What is a double check

A double check is a check given by two pieces at once with a single move. One piece attacks the king directly from its new square, and the second gives a discovered check, because the first one moved off its line.

A double check is a special case of a discovered check, but an especially strong one: the same piece moves, gives check and at the same time opens the line for the second piece.

Why a double check is so dangerous

There are three ways to defend against an ordinary check:

  1. move the king;
  2. block with one of your pieces;
  3. capture the checking piece.

Against a double check only one way is left: moving the king. You can't block: even if you cover one line, the second piece is still giving check. And you can't capture both pieces with one move either.

Important: if the king has no squares to escape to, a double check is immediately checkmate, even if both pieces are under attack.

How to find a double check

  1. Find your long-range piece (rook, bishop, queen) whose line to the king is blocked by one of your own pieces.
  2. Check whether the blocking piece can move away with check (that is, go to a square where it attacks the king too).
  3. If it can, that's a double check. Count the squares the opponent's king can go to.
  4. If the king has no safe squares, it's checkmate by double check.

Tips to spot the idea faster

For kids

Imagine two "sniper" pieces. The front one blocks the other, and the one behind keeps the king "in its sights". When the front piece jumps to a new square, it also shoots at the king, and right away the second one gets a clear shot from behind.

Against two shots at once, the king can only run away.

For adults

Look for positions where your piece both blocks the line of your long-range piece and can move to a square from which it gives check itself.

The most dangerous double checks are made by a knight (jumping at the king) and a bishop, because their new attack does not lie on the same line as the attack of the uncovered piece.

Examples

Try it yourself: make a move on the board. If you get stuck, press "Show solution".

1. Double check by knight and rook

Idea: the white knight on e4 blocks the e-file for the rook on e1. It can jump to f6, where it attacks the king itself (Nd6+ works the same way).

After Nf6+ two pieces give check at once: the knight from f6 and the rook from e1. The king has to move.

Solution: Double check: both the knight and the rook on e1 are giving check, so blocking is impossible and the king has to move.

2. Double check by bishop and rook

Idea: the white bishop on e2 blocks the attack of the rook on e1 against the king on e8. The bishop can move away with check along a diagonal, to b5 or to h5.

After Bb5+ the bishop on b5 gives check along the b5 - e8 diagonal, and at the same time the rook gives check along the open file. The king has to move to a free square.

Solution: Double check: the bishop checks along the diagonal and the rook along the e-file. The king has to move.

3. Checkmate by double check

Idea: all the squares next to the black king, except e7, are occupied by its own pieces and pawns. The white knight on e6 blocks the rook's attack along the file.

After Nc7# the knight gives check from c7, and the rook gives check along the open file (it also takes the e7 square away from the king). Against a simple discovered check Black could block with the knight on e7 or e5, but a double check can't be blocked, both pieces can't be captured with one move, and the king has nowhere to go: checkmate. Ng7# mates in the same way.

Solution: Checkmate by double check: the king has nowhere to go, blocking is impossible, and both pieces can't be captured with one move.