Fork (chess)

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a8 black rook
d7 black king
b6 white knight
g4 black pawn
f3 white rook
h3 white rook
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The knight forks the black king and rook. The pawn forks the white rooks.

In chess, a fork is a tactic whereby a single piece makes two or more direct attacks simultaneously. Most commonly two pieces are threatened, which is also sometimes called a double attack. The attacker usually aims to gain material by capturing one of the opponent's pieces. The defender often finds it difficult to counter two or more threats in a single move. The attacking piece is called the forking piece; the pieces attacked are said to be forked. A piece that is defended can still be forked, if the forking piece has a lower value.

Besides attacking pieces, a target of a fork can be a direct mating threat (for example, attacking an unprotected knight while simultaneously setting up a battery of queen and bishop to threaten mate). Or a target can be an implied threat (for example, a knight may attack an unprotected piece while simultaneously threaten to fork queen and rook).

Forks are often used as part of a combination which may involve other types of chess tactics as well.


Forking piece[edit]

The type of fork is named after the type of forking piece. For example, a knight fork is a knight move that attacks two or more opponent's pieces simultaneously. Any type of piece can perform a fork[note 1]—including the king—and any type of piece can be forked. A fork is most effective when it is forcing, such as when the king is put in check.

Knights are often used for forks. Their unique L-shaped move means that they can attack any other type of piece, including the powerful Queen, without being attacked by their targets.

The queen is also often used to fork, but since the queen is usually more valuable than the pieces it attacks, this typically gains material only when the pieces attacked are undefended or if one is undefended and the opposing king is checked. The possibility of a queen fork is a very real threat when the queen is in the open, as is often the case in endgames. If a player wants to force an exchange of queens, forking the opposing queen and king (or an undefended piece) with a protected queen can be useful.

Pawns other than rook pawns (those on the a- and h-files) can also be used to fork by attacking two enemy pieces diagonally—one to the left, the other to the right.

Example from a game[edit]

Tissir vs. Dreev, 2004
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a8 black rook
g8 black king
b7 black pawn
d7 black queen
f7 black pawn
g7 black bishop
h7 black pawn
g6 black pawn
c5 white pawn
d5 black pawn
a4 black pawn
e4 black knight
f4 white queen
a3 white pawn
f3 white pawn
a2 white bishop
d2 white bishop
g2 white pawn
h2 white pawn
c1 white rook
h1 white king
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Position after 33.Qf4


This example is from the first round of the FIDE World Chess Championship 2004 between Mohamed Tissir and Alexey Dreev.[1] After 33... Nf2+ 34. Kg1 Nd3, White resigned. In the final position the black knight forks the white queen and rook; after the queen moves away, Black will win the exchange.

Example from an opening[edit]

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a8 black rook
c8 black bishop
d8 black queen
e8 black king
f8 black bishop
h8 black rook
a7 black pawn
b7 black pawn
c7 black pawn
d7 black pawn
f7 black pawn
g7 black pawn
h7 black pawn
c6 black knight
f6 black knight
e5 black pawn
c4 white bishop
e4 white pawn
c3 white knight
f3 white knight
a2 white pawn
b2 white pawn
c2 white pawn
d2 white pawn
f2 white pawn
g2 white pawn
h2 white pawn
a1 white rook
c1 white bishop
d1 white queen
e1 white king
h1 white rook
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Position after 4.Nc3. Black can play 4...Nxe4 since he has a fork trick.
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a8 black rook
c8 black bishop
d8 black queen
e8 black king
f8 black bishop
h8 black rook
a7 black pawn
b7 black pawn
c7 black pawn
f7 black pawn
g7 black pawn
h7 black pawn
c6 black knight
d5 black pawn
e5 black pawn
c4 white bishop
e4 white knight
f3 white knight
a2 white pawn
b2 white pawn
c2 white pawn
d2 white pawn
f2 white pawn
g2 white pawn
h2 white pawn
a1 white rook
c1 white bishop
d1 white queen
e1 white king
h1 white rook
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After 4...Nxe4 5.Nxe4 d5, White is forked and Black will regain a piece.

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 4... Nxe4! due to the fork trick 5. Nxe4 d5—regaining either the bishop or the knight.

Escaping forks[edit]

Forks can possibly be escaped when the king is not in check. A forked piece such as the queen might check the enemy king, a zwischenzug, giving time to move the second forked piece to safety on the next move.

Other terms[edit]

A fork of the king and queen, the highest material-gaining fork possible, is sometimes called a royal fork. A fork of the opponent's king, queen, and one (or both) rooks is sometimes called a grand fork. A knight fork of the opponent's king, queen, and possibly other pieces is sometimes called a family fork or family check.

See also[edit]

Notes[edit]

  1. ^ Some sources apply the term fork only when a knight is the attacker, while if another piece is the attacker the tactic is called double attack, etc.

Citations[edit]

  1. ^ Tissir vs. Dreev, 2004 Chessgames.com

References[edit]

External links[edit]