In chess, a fork is a tactic in which a piece attacks multiple enemy pieces simultaneously. The attacker usually aims to capture one of the forked pieces. The defender often cannot counter every threat. A fork is most effective when it is forcing, such as when the king is put in check. A fork is a type of double attack.
A fork is an example of a double attack. The type of fork is named after the type of forking piece. For example, a fork by a knight is a knight fork. The attacked pieces are forked.[1] If the king is one of the attacked pieces, the term absolute fork is sometimes used. A fork not involving the enemy king is a relative fork.[2]
A fork of the king and queen, the highest material-gaining fork possible, is sometimes called a royal fork. A fork of the enemy king, queen, and one (or both) rooks is sometimes called a grand fork. A knight fork of the enemy king, queen, and possibly other pieces is sometimes called a family fork or family check.[3]
Any piece can deliver a fork. Forks are most often delivered by knights: a knight is not attacked by a piece it attacks except for an enemy knight, and it can be exchanged for a more valuable piece.[4][5]
Since the queen is usually more valuable than the pieces it attacks, a queen fork gains material only when the pieces attacked are undefended or if one of them is the king and the other is undefended.
| a | b | c | d | e | f | g | h | ||
| 8 |             | 8 | |||||||
| 7 | 7 | ||||||||
| 6 | 6 | ||||||||
| 5 | 5 | ||||||||
| 4 | 4 | ||||||||
| 3 | 3 | ||||||||
| 2 | 2 | ||||||||
| 1 | 1 | ||||||||
| a | b | c | d | e | f | g | h | ||
This example is from the first round of the FIDE World Chess Championship 2004 between Mohamed Tissir and Alexey Dreev.[6] After
White resigned. In the final position the black knight forks White's queen and rook; after the queen moves away, Black will win the exchange.
| a | b | c | d | e | f | g | h | ||
| 8 |  | 8 | |||||||
| 7 | 7 | ||||||||
| 6 | 6 | ||||||||
| 5 | 5 | ||||||||
| 4 | 4 | ||||||||
| 3 | 3 | ||||||||
| 2 | 2 | ||||||||
| 1 | 1 | ||||||||
| a | b | c | d | e | f | g | h | ||
This example is from the ninth round of the Clarin GP Final between Guillermo Soppe and Fernando Braga.[7] After
White resigned. The only move is 41.Ke2 which enables a royal fork with 41...Nc3+, winning the queen.
Position after 4.Nc3. Black can play 4...Nxe4 since he has a fork trick.
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After 4...Nxe4 5.Nxe4 d5, White is forked and Black will regain a piece.
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In the Two Knights Defense (1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6) after 4.Nc3, Black can eliminate White's e4-pawn immediately with
due to the fork trick
regaining either the bishop or the knight.
