Skewer (chess)

In chess, a skewer is an attack upon two pieces in a line and is similar to a pin. A skewer is the opposite of a pin; the difference is that in a skewer, the more valuable piece is the one under direct attack and the less valuable piece is behind it.[1] 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).[2] Only line pieces (i.e. bishops, rooks, and queens) can skewer; kings, knights, and pawns cannot.

Details

Compared to the pin, a passive action with only an implied threat, the skewer is a direct attack upon the more valuable piece, making it generally a much more powerful and effective tactic. The victim of a skewer often cannot avoid losing material; 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.

Skewers can be broken down into two types: absolute and relative. In an absolute skewer, the king is in check, therefore the check must be handled (under the rules of chess); whereas in a relative skewer, the pieces involved do not necessarily need to be addressed, but it is generally disadvantageous to not address the skewered piece.

Absolute skewer

abcdefgh
8
d7 black queen
e7 black king
d5 black bishop
e4 white king
f4 white rook
f3 white queen
8
77
66
55
44
33
22
11
abcdefgh
The white king is skewered by the black bishop, since after it moves out of check, 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.

Relative skewer

abcdefgh
8
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
77
66
55
44
33
22
11
abcdefgh
The black queen is skewered by the white bishop, since 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.

Examples from games

Short vs. Vaganian
abcdefgh
8
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
8
77
66
55
44
33
22
11
abcdefgh
Position after 51.Be5+

In the game Nigel ShortRafael Vaganian, Barcelona 1989,[3] White sacrifices a bishop to win a queen by a skewer. White has just played 51.Be5+ (see diagram), skewering Black's king and queen. If Black responds 51...Kxe5 to avoid the immediate loss of the queen, 52.Qc3+ wins the queen by another skewer. Black resigned in this position.[4]

Defence

abcdefgh
8
g8 black king
f7 black pawn
g7 black pawn
g6 black rook
c5 black pawn
c4 white pawn
e4 black bishop
c3 white pawn
d3 white rook
c2 white bishop
d2 white pawn
g2 black pawn
g1 white king
8
77
66
55
44
33
22
11
abcdefgh
Black has skewered White's rook and bishop, but White can turn the tables with the discovered attack 1.Rd8+ Kh7 2.Bxe4, winning Black’s bishop for free.

Skewers can be escaped by gaining a tempo with a credible threat. For example, if either defending piece leaves the skewer to give check, the other can be rescued on the next move. The skewer can also be reversed into a discovered attack; if the less valuable piece can attack the skewering piece, making a threat with the more valuable piece allows the defender to capture the attacker first (if the threat does not itself drive off the attacker).

If there is empty space between the skewering and the skewered pieces, it may be possible to convert the skewer into a pin by moving a lower-valued piece to intervene.

See also

References

  1. Brace, Edward R. (1977), An Illustrated Dictionary of Chess, Hamlyn Publishing Group, p. 261, ISBN 1-55521-394-4
  2. Reinfeld, Fred (1955). 1001 Winning Chess Sacrifices and Combinations. Wilshire Book Company. p. 151. ISBN 0-87980-111-5.
  3. "Nigel Short vs. Rafael Vaganian, Barcelona World Cup (1989)". Chessgames.com.
  4. Hooper & Whyld (1996), p. 374. skewer.

Bibliography

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