Skewer (chess)

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In chess, a skewer (or X-ray attack) is an attack upon two pieces in a line and is similar to a pin. In fact, a skewer is sometimes described as a "reverse pin"; the difference is that in a skewer, the more valuable piece is in front of the piece of lesser or equal value. The opponent is compelled to move the more valuable piece to avoid its capture, thereby exposing the less valuable piece which can then be captured (see chess piece relative value).[1] The long-range pieces (queen, rook, and bishop) can skewer.


Details[edit]

Skewers can be broken down into two types: absolute and relative. In an absolute skewer, the king is in check so the check must be dealt with (under the rules of chess). In a relative skewer, the piece under attack is not a king, so the side being skewered is not obligated under the rules to move the piece.

Relative skewer[edit]

a b c d e f g h
8
Chessboard480.svg
b7 black rook
f7 black king
e6 black pawn
f6 black pawn
d5 black queen
f4 white pawn
e3 white pawn
f3 white bishop
e2 white queen
f2 white king
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
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The black queen is skewered by the white bishop because if it moves, the bishop can capture the black rook

In this diagram, with Black to move, the black queen is skewered by White's bishop. To avoid capture of the queen, Black must move the queen, and on the next move, White can capture the rook. This is a relative skewer; Black is likely to move the queen, which is more valuable than the rook—but the choice is still available.

Absolute skewer[edit]

a b c d e f g h
8
Chessboard480.svg
d7 black queen
e7 black king
d5 black bishop
e4 white king
f4 white bishop
f3 white queen
8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h
The white king is skewered by the black bishop because when it moves, the bishop can capture the white queen

In this diagram, with White to move, the white king is skewered by the black bishop. This is an absolute skewer, because the rules of chess compel White to get out of check (if possible). After White chooses one of the handful of legal moves available, Black will capture the white queen.

Because the skewer is a direct attack upon the more valuable piece, it is generally a much more powerful and effective tactic than the pin. The victim of a skewer often cannot avoid losing material (though it may be possible if, for example, either piece can give check, thereby forcing the skewering side to move out of check instead of being able to capture either piece, or if it is possible to move a less valuable piece in the way); the only question is which material will be lost. The skewer occurs less often than the pin in actual play. When it does occur, however, it is often decisive.

Example from game[edit]

Short vs. Vaganian
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8
Chessboard480.svg
c8 white queen
b7 black pawn
g7 black queen
a6 black pawn
f6 black king
e5 white bishop
g5 black pawn
a4 white pawn
e4 black bishop
h3 white pawn
f2 white pawn
g2 white pawn
g1 white king
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7 7
6 6
5 5
4 4
3 3
2 2
1 1
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Position after 51.Be5+, after 51...Kxe5 52.Qc3+ skewers

In this 1989 game between Nigel Short and Rafael Vaganian, White sacrifices a bishop to win a queen by a skewer.[2] White has just moved 51. Be5+. If Black moves 51...Kxe5 to avoid the immediate loss of the queen, 52.Qc3+ wins the queen by a skewer. Black resigned in this position (Hooper & Whyld 1992:374).

See also[edit]

Notes[edit]

  1. ^ Reinfeld, Fred (1955). 1001 Winning Chess Sacrifices and Combinations. Wilshire Book Company. p. 151. ISBN 0-87980-111-5. 
  2. ^ Short vs Vaganian

References[edit]

External links[edit]