What is the difference between a fork and a double attack?

A fork is a double attack made by a single piece. A double attack can also come from one piece moving and another piece behind it opening a line.

Do both threats need to be captures?

No. A threat of mate, a threat to promote or a threat to trap a piece can be the second threat, and those are often the hardest to see.

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Double attacks: creating two threats in one move

A double attack is any move that creates two threats at the same time. Forks, discovered attacks, and moves that threaten mate while also hitting a piece all belong to this family — the shared idea is that the defender only gets one move.

The most useful version for practical play is the quiet double attack: no check, no capture, but two pieces are suddenly hanging and only one can be rescued.

Double attacks live off loose pieces. Almost every double attack you will ever play is aimed at pieces that were undefended or defended only once.

Rc4 attacks the rook on c8 down the file and the knight on g4 along the fourth rank. Both black pieces are loose, so one of them is lost.

How to spot it

Name the opponent's loose pieces every move. Two loose pieces is an invitation to look for a square that hits both.
Consider threats other than captures: mate threats, promotion threats and trapping threats all count as the second attack.
Look for moves that gain a tempo and improve a piece at the same time — those are the moves that turn into double attacks.
If one threat is not enough, ask whether a forcing move first can create the second weakness.

Practise this pattern

Play the winning move on a real board in verified double attack positions, with hints and worked solutions.

Start the exercises

How to defend against it

Keep your pieces defended; connected pieces are hard to double-attack.
Answer a double attack by defending the piece that also parries the other threat, or by counter-attacking with a bigger threat.
Look for a move that saves one piece while defending the other — an in-between move or a check often does both.
Simplify: trading off the attacking piece usually ends the whole problem.

Common mistakes

Making two threats the opponent can meet with one defensive move.
Playing a double attack that costs a tempo you needed elsewhere, so the opponent's counter-threat lands first.
Missing that one of the two 'targets' was defended all along.

Frequently asked questions

What is the difference between a fork and a double attack?: A fork is a double attack made by a single piece. A double attack can also come from one piece moving and another piece behind it opening a line.
Do both threats need to be captures?: No. A threat of mate, a threat to promote or a threat to trap a piece can be the second threat, and those are often the hardest to see.