A double attack is an attack on two targets with one move. The targets vary: two pieces, a piece and the king, a mate threat and a piece. The opponent can parry only one threat.
A fork is a double attack by a single piece. But a double attack can also arise differently: for example, when one piece moves away and opens a line for another (a discovered attack).
The queen's double attack
The queen moves in all directions, so it is best suited for double attacks. The classic is a check to the king combined with an attack on an undefended piece.
1. 2.
The main target is undefended pieces
Almost every double attack is aimed at undefended pieces. A defended piece can be left alone by the opponent: after the capture they win material back. So:
- keep your pieces protected;
- look for undefended pieces in your opponent's position — they are candidate targets.
Chess players have a saying: “Loose pieces drop off.”
Other kinds of double attack
- Mate threat + attack on a piece. The opponent has to defend against mate and loses a piece.
- Discovered attack. A piece leaves the line, unmasking another piece's attack, and itself attacks a second target.
- Discovered check. The same, but it is a check to the king that is uncovered — the strongest version. If both pieces give check, it is a double check (“Check”).